Android Thread第二次Thread.start()报错的疑问

本文探讨了Java线程重复启动导致的IllegalThreadStateException问题,并提供了通过使用Runnable接口和无限循环来解决此问题的方法。此外,介绍了如何避免无限循环性能问题的解决方案。

http://blog.youkuaiyun.com/libaineu2004/article/details/25692655


文章来源:http://my.oschina.net/ldaga/blog/65213

http://blog.youkuaiyun.com/jspamd/article/details/5262894

网上说Thread不需要stop()的原因是因为运行到尾部就会自动释放,而代码:

01 Thread myThread = new Thread(new Runnable() {
02  
03     @Override
04     public void run() {
05         // TODO Auto-generated method stub
06         Log.i("thread""" + count);
07         while (runable) {
08              
09                 count++;
10                 try {
11                     Thread.sleep(100);
12                 catch (Exception e) {
13                 }
14                 Message msg = mhandler.obtainMessage(FLAG_UPDATE, 00);
15                 mhandler.sendMessage(msg);
16             }
17          
18     }
19 });

在第二次start()的时候,系统抛出异常:java.lang.IllegalThreadStateException: Thread already started.

这是个很悲催的事情,而我现在也只能,这样:

01 Thread myThread = new Thread(new Runnable() {
02  
03     @Override
04     public void run() {
05         // TODO Auto-generated method stub
06         Log.i("thread""" + count);
07         while (true) {
08             if (runable) {
09                 count++;
10                 try {
11                     Thread.sleep(100);
12                 catch (Exception e) {
13                 }
14                 Message msg = mhandler.obtainMessage(FLAG_UPDATE, 00);
15                 mhandler.sendMessage(msg);
16             }
17         }
18     }
19 });

        不过这样的牺牲就是有线程在无限循环...性能...

        不知列位大牛是怎么处理这里的。

 

这个已经解决了,可以写一个继承Thread的类,或者写一个Runnable,然后再new Thread(xx).start();就可以了,回头看一下,真小白啊!


新代码如下:

创建一个Runnable,用于Thread执行

1 Runnable sendable = new Runnable() {
2  
3     @Override
4     public void run() {
5         // TODO Auto-generated method stub
6  
7     }
8 };
run方法中写上需要操作的逻辑,然后这样调用:

1 new Thread(sendable).start();
这样,每次需要调用的时候会重新new一个Thread,大体是这样,但可以无限次数运行。
build.gradle(app):apply plugin: 'com.android.application' android { compileSdkVersion 28 defaultConfig { applicationId "com.hik.netsdk.SimpleDemo" minSdkVersion 15 targetSdkVersion 28 versionCode 11 versionName "3.0" testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner" vectorDrawables.useSupportLibrary = true multiDexEnabled true ndk { abiFilters "armeabi-v7a","arm64-v8a" } } buildTypes { release { minifyEnabled false proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro' } } sourceSets { main { res.srcDirs = [ 'src/main/res', 'src/main/res/layout/DevMgtUI', 'src/main/res/layout/BusinessUI' ] jniLibs.srcDirs = ['libs'] } } compileOptions { sourceCompatibility = '1.8' targetCompatibility = '1.8' } buildToolsVersion = '28.0.3' } dependencies { implementation files('libs/HCNetSDK.jar') implementation files('libs/PlayerSDK_hcnetsdk.jar') implementation fileTree(include: ['*.jar'], dir: 'libs') implementation 'com.squareup.okhttp3:okhttp:4.9.1' implementation 'androidx.appcompat:appcompat:1.4.1' implementation 'com.google.android.material:material:1.5.0' // 替代 design implementation 'androidx.constraintlayout:constraintlayout:2.1.3' implementation 'androidx.legacy:legacy-support-v4:1.0.0' // 替代 support-v4 testImplementation 'junit:junit:4.12' androidTestImplementation 'androidx.test:runner:1.4.0' androidTestImplementation 'androidx.test.espresso:espresso-core:3.4.0' implementation 'io.github.ezviz-open:ezviz-sdk:5.20' // implementation 'com.ezviz:sdk:4.19.5' compile 'com.ezviz.sdk:ezuikit:2.2.1' implementation files('libs/PlayerSDK.jar') implementation fileTree(dir: 'libs', include: ['*.jar', '*.aar']) implementation files('libs/ERTC_Android_SDK_1.5.0.1.aar') // 添加必要支持库 implementation 'com.squareup.okhttp3:okhttp:3.12.1' implementation 'com.google.code.gson:gson:2.8.5' // 海康SDK - 确保已添加 implementation files('libs/hikvision-sdk.jar') implementation 'com.google.android.exoplayer:exoplayer-core:2.18.7' implementation 'com.google.android.exoplayer:exoplayer-hls:2.18.7' implementation 'com.google.android.exoplayer:exoplayer-ui:2.18.7' implementation 'com.google.android.exoplayer:extension-okhttp:2.18.7' } MainActivity:package com.hik.netsdk.SimpleDemo.View; import android.app.AlertDialog; import android.content.Intent; import android.graphics.PixelFormat; import android.net.Uri; import android.os.Bundle; import android.os.Handler; import android.os.Looper; import android.os.Message; import android.util.Log; import android.view.Menu; import android.view.MenuItem; import android.view.SurfaceHolder; import android.view.SurfaceView; import android.view.View; import android.widget.EditText; import android.widget.ImageButton; import android.widget.ProgressBar; import android.widget.RelativeLayout; import android.widget.Toast; import androidx.appcompat.app.AppCompatActivity; import androidx.appcompat.widget.Toolbar; import androidx.core.view.GravityCompat; import androidx.drawerlayout.widget.DrawerLayout; import androidx.media3.common.Player; // ExoPlayer 相关导入 import androidx.media3.exoplayer.ExoPlayer; import androidx.media3.exoplayer.SimpleExoPlayer; import androidx.media3.common.MediaItem; import androidx.media3.datasource.DataSource; import androidx.media3.datasource.DefaultHttpDataSource; import androidx.media3.exoplayer.source.MediaSource; import androidx.media3.exoplayer.source.hls.HlsMediaSource; import com.google.android.exoplayer2.upstream.DataSource; import com.google.android.exoplayer2.upstream.DefaultHttpDataSource; import com.google.gson.Gson; import com.hik.netsdk.SimpleDemo.R; import com.hik.netsdk.SimpleDemo.View.DevMgtUI.AddDevActivity; import com.videogo.errorlayer.ErrorInfo; import com.videogo.openapi.EZConstants; import com.videogo.openapi.EZOpenSDK; import com.videogo.openapi.EZPlayer; import org.json.JSONException; import org.json.JSONObject; import java.io.IOException; import java.util.concurrent.TimeUnit; import okhttp3.MediaType; import okhttp3.OkHttpClient; import okhttp3.Request; import okhttp3.RequestBody; import okhttp3.Response; public class MainActivity extends AppCompatActivity implements SurfaceHolder.Callback { // 核心参数 private String mDeviceSerial; private String mVerifyCode; private int mCameraNo = 1; private boolean isEzDevice = false; // 萤石云相关参数 private String mAppKey = "a794d58c13154caeb7d2fbb5c3420c65"; private String mAccessToken = ""; // UI组件 private SurfaceView mPreviewSurface; private SurfaceHolder mSurfaceHolder; private Toolbar m_toolbar; private ProgressBar mProgressBar; private RelativeLayout mControlLayout; private ImageButton mRotateButton; // 播放器相关 private SimpleExoPlayer mExoPlayer; private String mPlaybackUrl; private final OkHttpClient mHttpClient = new OkHttpClient.Builder() .connectTimeout(15, TimeUnit.SECONDS) .readTimeout(15, TimeUnit.SECONDS) .build(); // 播放器状态监听器 private final Player.Listener mPlayerListener = new Player.Listener() { @Override public void onPlaybackStateChanged(int state) { switch (state) { case Player.STATE_READY: mProgressBar.setVisibility(View.GONE); Log.d("ExoPlayer", "播放准备就绪"); break; case Player.STATE_BUFFERING: mProgressBar.setVisibility(View.VISIBLE); Log.d("ExoPlayer", "缓冲中..."); break; case Player.STATE_ENDED: Log.d("ExoPlayer", "播放结束"); break; case Player.STATE_IDLE: Log.d("ExoPlayer", "空闲状态"); break; } } @Override public void onPlayerError(com.google.android.exoplayer2.PlaybackException error) { Log.e("ExoPlayer", "播放错误: " + error.getMessage()); handleError("播放错误: " + error.getMessage(), -1); } }; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // 初始化UI组件 initUIComponents(); // 获取启动参数 parseIntentParams(); // 初始化SDK initSDK(); // 参数校验 if (mDeviceSerial == null || mDeviceSerial.isEmpty()) { showErrorAndFinish("设备序列号不能为空"); return; } Log.d("MainActivity", "onCreate完成: isEzDevice=" + isEzDevice); } private void initUIComponents() { // 基础UI m_toolbar = findViewById(R.id.toolbar); setSupportActionBar(m_toolbar); // 预览相关UI mPreviewSurface = findViewById(R.id.realplay_sv); mSurfaceHolder = mPreviewSurface.getHolder(); mSurfaceHolder.addCallback(this); mSurfaceHolder.setFormat(PixelFormat.TRANSLUCENT); mProgressBar = findViewById(R.id.liveProgressBar); mControlLayout = findViewById(R.id.rl_control); mRotateButton = findViewById(R.id.ib_rotate2); // 设置旋转按钮点击事件 mRotateButton.setOnClickListener(v -> changeScreen()); // 隐藏管理UI DrawerLayout drawer = findViewById(R.id.drawer_layout); if (drawer != null) { drawer.setVisibility(View.GONE); } if (m_toolbar != null) { m_toolbar.setVisibility(View.GONE); } // 初始化控制按钮 initControlButtons(); Log.d("UI", "UI组件初始化完成"); } private void parseIntentParams() { // 获取Intent参数 Intent intent = getIntent(); isEzDevice = true; // 只支持萤石设备 mAccessToken = intent.getStringExtra("accessToken"); // 优先使用bundle Bundle bundle = intent.getExtras(); if (bundle != null) { mDeviceSerial = bundle.getString("devSn"); mVerifyCode = bundle.getString("verifyCode"); mCameraNo = bundle.getInt("cameraNo", 1); } // 兼容直接Extra方式 if (mDeviceSerial == null) mDeviceSerial = intent.getStringExtra("devSn"); if (mVerifyCode == null) mVerifyCode = intent.getStringExtra("verifyCode"); if (mCameraNo == 0) mCameraNo = intent.getIntExtra("cameraNo", 1); Log.d("Params", "设备序列号: " + mDeviceSerial + ", 通道号: " + mCameraNo); } private void initSDK() { try { // 使用反射检查初始化状态 boolean isInitialized = false; try { // 尝试获取实例 EZOpenSDK instance = EZOpenSDK.getInstance(); if (instance != null) { isInitialized = true; } } catch (Exception e) { // 捕获未初始化的异常 isInitialized = false; } // 未初始化进行初始化 if (!isInitialized) { EZOpenSDK.initLib(getApplication(), mAppKey); Log.d("EZSDK", "萤石SDK初始化完成"); } // 设置AccessToken if (mAccessToken != null && !mAccessToken.isEmpty()) { EZOpenSDK.getInstance().setAccessToken(mAccessToken); Log.d("EZToken", "AccessToken设置成功"); } else { Log.w("EZToken", "AccessToken缺失!"); } } catch (Exception e) { Log.e("EZSDK", "萤石SDK初始化失败", e); handleError("萤石SDK初始化失败: " + e.getMessage(), -1); } } private void initControlButtons() { // 云台控制按钮 findViewById(R.id.ptz_top_btn).setOnClickListener(v -> controlPTZ("UP")); findViewById(R.id.ptz_bottom_btn).setOnClickListener(v -> controlPTZ("DOWN")); findViewById(R.id.ptz_left_btn).setOnClickListener(v -> controlPTZ("LEFT")); findViewById(R.id.ptz_right_btn).setOnClickListener(v -> controlPTZ("RIGHT")); // 变焦控制 findViewById(R.id.focus_add).setOnClickListener(v -> controlZoom("ZOOM_IN")); findViewById(R.id.foucus_reduce).setOnClickListener(v -> controlZoom("ZOOM_OUT")); // 水平布局控制按钮 findViewById(R.id.ptz_top_btn2).setOnClickListener(v -> controlPTZ("UP")); findViewById(R.id.ptz_bottom_btn2).setOnClickListener(v -> controlPTZ("DOWN")); findViewById(R.id.ptz_left_btn2).setOnClickListener(v -> controlPTZ("LEFT")); findViewById(R.id.ptz_right_btn2).setOnClickListener(v -> controlPTZ("RIGHT")); // 添加萤石云特有功能按钮 // findViewById(R.id.btn_record).setOnClickListener(v -> startLocalRecord()); // findViewById(R.id.btn_stop_record).setOnClickListener(v -> stopLocalRecord()); // findViewById(R.id.btn_capture).setOnClickListener(v -> capturePicture()); Log.d("Controls", "控制按钮初始化完成"); } @Override public void surfaceCreated(SurfaceHolder holder) { Log.d("Surface", "Surface created"); // 获取播放地址并开始播放 new Thread(this::fetchPlaybackUrl).start(); } @Override public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) { Log.d("Surface", "Surface changed: " + width + "x" + height); if (mExoPlayer != null) { mExoPlayer.setVideoSurfaceHolder(holder); } } @Override public void surfaceDestroyed(SurfaceHolder holder) { Log.d("Surface", "Surface destroyed"); stopPreview(); } // ======================== 播放地址获取与播放 ======================== private void fetchPlaybackUrl() { try { // 构建请求参数 JSONObject params = new JSONObject(); params.put("accessToken", mAccessToken); params.put("deviceSerial", mDeviceSerial); params.put("channelNo", mCameraNo); params.put("protocol", 2); // 使用HLS协议 if (mVerifyCode != null && !mVerifyCode.isEmpty()) { params.put("code", mVerifyCode); } params.put("expireTime", 7200); // 2小有效期 // 创建请求体 RequestBody body = RequestBody.create( MediaType.parse("application/json"), params.toString() ); // 创建请求 Request request = new Request.Builder() .url("https://open.ys7.com/api/lapp/v2/live/address/get") .post(body) .build(); // 执行请求 try (Response response = mHttpClient.newCall(request).execute()) { if (!response.isSuccessful()) { handleError("获取播放地址失败: " + response.code(), response.code()); return; } // 解析响应 String responseBody = response.body().string(); JSONObject json = new JSONObject(responseBody); if ("200".equals(json.getString("code"))) { JSONObject data = json.getJSONObject("data"); mPlaybackUrl = data.getString("url"); Log.d("PlaybackURL", "获取到播放地址: " + mPlaybackUrl); // 在主线程初始化播放器 runOnUiThread(this::initExoPlayer); } else { handleError("API错误: " + json.getString("msg"), json.getInt("code")); } } } catch (JSONException | IOException e) { Log.e("FetchURL", "获取播放地址异常", e); handleError("获取播放地址异常: " + e.getMessage(), -1); } } private void initExoPlayer() { // 释放现有播放器 if (mExoPlayer != null) { mExoPlayer.release(); } // 创建新的播放器实例 mExoPlayer = new SimpleExoPlayer.Builder(this).build(); mExoPlayer.addListener(mPlayerListener); mExoPlayer.setVideoSurfaceHolder(mSurfaceHolder); // 创建媒体源 DataSource.Factory dataSourceFactory = new DefaultHttpDataSource.Factory(); MediaSource mediaSource = new HlsMediaSource.Factory(dataSourceFactory) .createMediaSource(MediaItem.fromUri(Uri.parse(mPlaybackUrl))); // 准备播放 mExoPlayer.setMediaSource(mediaSource); mExoPlayer.prepare(); mExoPlayer.setPlayWhenReady(true); mProgressBar.setVisibility(View.VISIBLE); Log.d("ExoPlayer", "播放器初始化完成,开始播放"); } // ======================== 萤石云控制方法 ======================== private int mapDirection(String direction) { switch (direction) { // case "UP": return EZCloudControl.DIRECTION_UP; // case "DOWN": return EZCloudControl.DIRECTION_DOWN; // case "LEFT": return EZCloudControl.DIRECTION_LEFT; // case "RIGHT": return EZCloudControl.DIRECTION_RIGHT; // case "ZOOM_IN": return EZCloudControl.DIRECTION_ZOOM_IN; // case "ZOOM_OUT": return EZCloudControl.DIRECTION_ZOOM_OUT; default: return -1; } } // 修改控制方法 private void controlPTZ(String direction) { int directionCode = mapDirection(direction); if (directionCode == -1) return; // 开始控制 // EZCloudControl.startPTZControl( // mAccessToken, // mDeviceSerial, // mCameraNo, // directionCode, // EZCloudControl.SPEED_MEDIUM, // 中等速度 // new EZCloudControl.ControlCallback() { // @Override // public void onSuccess(String response) { // Log.d("PTZControl", "开始云台控制成功: " + direction); // // // 300ms后停止控制 // new Handler(Looper.getMainLooper()).postDelayed(() -> { // stopPTZControl(directionCode); // }, 300); // } // // @Override // public void onFailure(String error) { // Log.e("PTZControl", "开始云台控制失败: " + error); // handleError("云台控制失败: " + error, -1); // } // }); } // private void stopPTZControl(int directionCode) { // EZCloudControl.stopPTZControl( // mAccessToken, // mDeviceSerial, // mCameraNo, // directionCode, // new EZCloudControl.ControlCallback() { // @Override // public void onSuccess(String response) { // Log.d("PTZControl", "停止云台控制成功"); // } // // @Override // public void onFailure(String error) { // Log.e("PTZControl", "停止云台控制失败: " + error); // // 可选择重试或其他处理 // } // }); // } private void controlZoom(String command) { String direction = "ZOOM_IN".equals(command) ? "ZOOM_IN" : "ZOOM_OUT"; controlPTZ(direction); } // ======================== 萤石云扩展功能 ======================== // 开始本地录像 private void startLocalRecord() { // 这里需要根据实际需求实现 Toast.makeText(this, "开始录像", Toast.LENGTH_SHORT).show(); } // 停止本地录像 private void stopLocalRecord() { // 这里需要根据实际需求实现 Toast.makeText(this, "停止录像", Toast.LENGTH_SHORT).show(); } // 截图 private void capturePicture() { // 这里需要根据实际需求实现 Toast.makeText(this, "截图已保存", Toast.LENGTH_SHORT).show(); } // ======================== 通用功能方法 ======================== public void changeScreen(View view) { changeScreen(); } private void changeScreen() { if (mControlLayout.getVisibility() == View.VISIBLE) { mControlLayout.setVisibility(View.GONE); } else { mControlLayout.setVisibility(View.VISIBLE); } } private void handleError(String message, int errorCode) { String fullMessage = message + " (错误码: " + errorCode + ")"; // 萤石云特有错误码处理 switch (errorCode) { case 400001: fullMessage = "AccessToken无效"; break; case 400002: fullMessage = "设备不存在"; break; case 400007: fullMessage = "设备不在线"; break; case 400034: fullMessage = "验证码错误"; break; case 400035: fullMessage = "设备已被自己添加"; break; case 400036: fullMessage = "设备已被别人添加"; break; default: fullMessage = "萤石云错误: " + errorCode; } new AlertDialog.Builder(this) .setTitle("预览失败") .setMessage(fullMessage) .setPositiveButton("确定", (d, w) -> finish()) .setCancelable(false) .show(); } private void showErrorAndFinish(String message) { Toast.makeText(this, message, Toast.LENGTH_LONG).show(); new Handler().postDelayed(this::finish, 3000); } private void stopPreview() { if (mExoPlayer != null) { mExoPlayer.release(); mExoPlayer = null; Log.d("Preview", "预览已停止"); } } @Override protected void onDestroy() { super.onDestroy(); stopPreview(); Log.d("Lifecycle", "onDestroy"); } @Override protected void onPause() { super.onPause(); if (mExoPlayer != null) { mExoPlayer.setPlayWhenReady(false); Log.d("Lifecycle", "暂停播放"); } } @Override protected void onResume() { super.onResume(); if (mExoPlayer != null) { mExoPlayer.setPlayWhenReady(true); Log.d("Lifecycle", "恢复播放"); } } @Override public void onBackPressed() { DrawerLayout drawer = findViewById(R.id.drawer_layout); if (drawer != null && drawer.isDrawerOpen(GravityCompat.START)) { drawer.closeDrawer(GravityCompat.START); } else { super.onBackPressed(); } } @Override public boolean onCreateOptionsMenu(Menu menu) { getMenuInflater().inflate(R.menu.menu_main_opt, menu); return true; } @Override public boolean onOptionsItemSelected(MenuItem item) { if (item.getItemId() == R.id.action_1) { startActivity(new Intent(this, AddDevActivity.class)); return true; } return super.onOptionsItemSelected(item); } } 依据上述依赖和代码解决报错:Cannot resolve symbol 'media3'(报错8次)
最新发布
06-22
<think>根据报错信息“Cannotresolvesymbol'media3'”,我们可以推断出项目中没有正确引入AndroidXMedia3库。虽然我们在build.gradle中添加了ExoPlayer的依赖,但是注意在代码中导入的是`androidx.media3`开头的包,而当前build.gradle中引入的ExoPlayer库的GroupID是`com.google.android.exoplayer`,这实际上是旧版的ExoPlayer(非AndroidXMedia3版本)。解决方案有两种:1.将代码中所有`androidx.media3`的导入改为`com.google.android.exoplayer`(即使用旧版ExoPlayer的包名),并调整API使用方式(因为旧版和新版API有差异)。2.升级到AndroidXMedia3版本的ExoPlayer,并修改依赖。考虑到我们之前已经尝试迁移到AndroidX,并且希望使用最新的库,这里选择第二种方案。步骤:1.修改build.gradle文件,将ExoPlayer依赖替换为AndroidXMedia3版本。2.调整代码中与Media3相关的内容(主要是包名和部分API可能有变动)。具体操作:第一步:更新build.gradle中的ExoPlayer依赖为Media3版本。注意:Media3将ExoPlayer整合到了新的库中,因此我们需要使用新的依赖项。在build.gradle的dependencies部分,将原有的ExoPlayer依赖替换为:```implementation"androidx.media3:media3-exoplayer:1.2.1"implementation"androidx.media3:media3-exoplayer-hls:1.2.1"implementation"androidx.media3:media3-ui:1.2.1"implementation"androidx.media3:media3-datasource-okhttp:1.2.1"```第二步:在代码中,将原本的`com.google.android.exoplayer2`和`androidx.media3`的混合导入统一为`androidx.media3`的导入。但是,我们注意到在代码中已经使用了`androidx.media3`的导入,所以只需确保依赖正确即可。然而,由于我们之前使用的是`com.google.android.exoplayer:exoplayer-core:2.18.7`等,这些库的包名是`com.google.android.exoplayer2`,而Media3的包名是`androidx.media3`,所以我们需要将代码中所有ExoPlayer相关的导入从`com.google.android.exoplayer2`改为`androidx.media3`。例如:原代码:importcom.google.android.exoplayer2.SimpleExoPlayer;importcom.google.android.exoplayer2.MediaItem;...改为:importandroidx.media3.exoplayer.SimpleExoPlayer;importandroidx.media3.common.MediaItem;...但是,在提供的代码中,实际上已经使用了`androidx.media3`的导入(如`importandroidx.media3.exoplayer.SimpleExoPlayer;`),所以我们需要确保依赖的库是Media3版本。因此,我们只需修改build.gradle中的依赖,然后同步项目。另外,注意Media3的版本选择,目前最新稳定版是1.2.1(截至2024年初)。第三步:由于Media3的API与旧版ExoPlayer有一些不同,我们可能需要调整代码。例如,创建`SimpleExoPlayer`的方式在Media3中有所改变。在Media3中,创建播放器的方式:mExoPlayer=newExoPlayer.Builder(context).build();注意:在Media3中,`SimpleExoPlayer`已经被移除,统一使用`ExoPlayer`接口,实现类也是`ExoPlayer`(通过Builder构建)。因此,我们需要将代码中的`SimpleExoPlayer`替换为`ExoPlayer`。修改步骤:1.将`SimpleExoPlayer`类型的变量改为`ExoPlayer`。2.使用`newExoPlayer.Builder(context).build()`来创建播放器实例。3.检查其他API的变化,例如设置视频表面现在使用`setVideoSurfaceHolder`方法(在Media3中,这个方法在`ExoPlayer`接口中)。具体修改如下:在MainActivity中:-将成员变量`privateSimpleExoPlayermExoPlayer;`改为`privateExoPlayermExoPlayer;`-在`initExoPlayer`方法中,创建播放器的代码改为:mExoPlayer=newExoPlayer.Builder(this).build();另外,注意`MediaSource`的创建也有变化。在Media3中,我们使用`HlsMediaSource`的方式已经改变,现在推荐使用`MediaItem`和`MediaSource.Factory`。创建HLS媒体源的方式:```javaMediaItemmediaItem=MediaItem.fromUri(Uri.parse(mPlaybackUrl));MediaSourcemediaSource=newHlsMediaSource.Factory(dataSourceFactory).createMediaSource(mediaItem);```但是,在Media3中,我们不需要直接创建`HlsMediaSource`,而是使用`ExoPlayer`的`setMediaItem`或`setMediaSource`方法,它内部会自动根据媒体项的格式选择对应的媒体源。因此,我们可以简化:```javamExoPlayer.setMediaItem(MediaItem.fromUri(Uri.parse(mPlaybackUrl)));mExoPlayer.prepare();```所以,我们可以删除显式创建`HlsMediaSource`的代码。修改后的`initExoPlayer`方法:```javaprivatevoidinitExoPlayer(){//释放现有播放器if(mExoPlayer!=null){mExoPlayer.release();}//创建新的播放器实例mExoPlayer=newExoPlayer.Builder(this).build();mExoPlayer.addListener(mPlayerListener);mExoPlayer.setVideoSurfaceHolder(mSurfaceHolder);//创建媒体项并设置MediaItemmediaItem=MediaItem.fromUri(Uri.parse(mPlaybackUrl));mExoPlayer.setMediaItem(mediaItem);mExoPlayer.prepare();mExoPlayer.play();//相当于setPlayWhenReady(true)mProgressBar.setVisibility(View.VISIBLE);Log.d("ExoPlayer","播放器初始化完成,开始播放");}```同,注意监听器接口也有变化。在Media3中,监听器现在是`Player.Listener`,我们之前已经使用了`Player.Listener`,所以这部分代码可以保持不变。但是,注意在Media3中,`Player`接口位于`androidx.media3.common.Player`。总结修改点:1.更新build.gradle依赖为Media3版本。2.将播放器变量类型从`SimpleExoPlayer`改为`ExoPlayer`(注意:`ExoPlayer`是一个接口,位于`androidx.media3.exoplayer.ExoPlayer`)。3.修改播放器的创建方式。4.修改媒体源的设置方式(使用`MediaItem`)。5.确保所有导入的包都是`androidx.media3`下的。由于代码中已经有一些`androidx.media3`的导入,所以只需调整依赖和播放器创建方式即可。最后,同步项目并清理构建(Build->CleanProject,Build->RebuildProject)以确保更改生效。下面我们具体修改代码:</think>### 解决方案:解决 "Cannot resolve symbol 'media3'" 错误 这个错误是因为项目没有正确导入 AndroidX Media3 库。以下是完整的解决方案: #### 1. 更新 `build.gradle` 依赖 ```groovy dependencies { // 移除旧版 ExoPlayer 依赖 implementation 'com.google.android.exoplayer:exoplayer-core:2.18.7' implementation 'com.google.android.exoplayer:exoplayer-hls:2.18.7' implementation 'com.google.android.exoplayer:exoplayer-ui:2.18.7' implementation 'com.google.android.exoplayer:extension-okhttp:2.18.7' // 添加 AndroidX Media3 依赖 implementation "androidx.media3:media3-exoplayer:1.2.1" implementation "androidx.media3:media3-exoplayer-hls:1.2.1" implementation "androidx.media3:media3-ui:1.2.1" implementation "androidx.media3:media3-datasource-okhttp:1.2.1" // 其他依赖保持不变... } ``` #### 2. 更新 `MainActivity` 中的导入语句 ```java // 替换这些导入 import com.google.android.exoplayer2.ExoPlayer; import com.google.android.exoplayer2.MediaItem; import com.google.android.exoplayer2.Player; import com.google.android.exoplayer2.SimpleExoPlayer; import com.google.android.exoplayer2.source.MediaSource; import com.google.android.exoplayer2.source.hls.HlsMediaSource; import com.google.android.exoplayer2.upstream.DataSource; import com.google.android.exoplayer2.upstream.DefaultHttpDataSource; // 使用这些 AndroidX Media3 导入 import androidx.media3.common.MediaItem; import androidx.media3.common.Player; import androidx.media3.exoplayer.ExoPlayer; import androidx.media3.exoplayer.hls.HlsMediaSource; import androidx.media3.exoplayer.source.MediaSource; import androidx.media3.datasource.DataSource; import androidx.media3.datasource.DefaultHttpDataSource; import androidx.media3.datasource.okhttp.OkHttpDataSource; ``` #### 3. 更新播放器初始化代码 ```java private void initExoPlayer() { // 释放现有播放器 if (mExoPlayer != null) { mExoPlayer.release(); } // 创建新的播放器实例 (AndroidX Media3) mExoPlayer = new ExoPlayer.Builder(this).build(); mExoPlayer.addListener(mPlayerListener); mExoPlayer.setVideoSurfaceHolder(mSurfaceHolder); // 创建媒体源 DataSource.Factory dataSourceFactory = new DefaultHttpDataSource.Factory(); MediaSource mediaSource = new HlsMediaSource.Factory(dataSourceFactory) .createMediaSource(MediaItem.fromUri(Uri.parse(mPlaybackUrl))); // 准备播放 mExoPlayer.setMediaSource(mediaSource); mExoPlayer.prepare(); mExoPlayer.play(); // 相当于 setPlayWhenReady(true) mProgressBar.setVisibility(View.VISIBLE); Log.d("ExoPlayer", "播放器初始化完成,开始播放"); } ``` #### 4. 更新播放器监听器 ```java // 播放器状态监听器 private final Player.Listener mPlayerListener = new Player.Listener() { @Override public void onPlaybackStateChanged(int state) { switch (state) { case Player.STATE_READY: mProgressBar.setVisibility(View.GONE); Log.d("ExoPlayer", "播放准备就绪"); break; case Player.STATE_BUFFERING: mProgressBar.setVisibility(View.VISIBLE); Log.d("ExoPlayer", "缓冲中..."); break; case Player.STATE_ENDED: Log.d("ExoPlayer", "播放结束"); break; case Player.STATE_IDLE: Log.d("ExoPlayer", "空闲状态"); break; } } @Override public void onPlayerError(PlaybackException error) { Log.e("ExoPlayer", "播放错误: " + error.getMessage()); handleError("播放错误: " + error.getMessage(), -1); } }; ``` ### 完整修复后的 `MainActivity` 关键部分 ```java package com.hik.netsdk.SimpleDemo.View; import android.app.AlertDialog; import android.content.Intent; import android.graphics.PixelFormat; import android.net.Uri; import android.os.Bundle; import android.os.Handler; import android.os.Looper; import android.util.Log; import android.view.Menu; import android.view.MenuItem; import android.view.SurfaceHolder; import android.view.SurfaceView; import android.view.View; import android.widget.ImageButton; import android.widget.ProgressBar; import android.widget.RelativeLayout; import android.widget.Toast; import androidx.appcompat.app.AppCompatActivity; import androidx.appcompat.widget.Toolbar; import androidx.core.view.GravityCompat; import androidx.drawerlayout.widget.DrawerLayout; // AndroidX Media3 导入 import androidx.media3.common.MediaItem; import androidx.media3.common.PlaybackException; import androidx.media3.common.Player; import androidx.media3.datasource.DataSource; import androidx.media3.datasource.DefaultHttpDataSource; import androidx.media3.exoplayer.ExoPlayer; import androidx.media3.exoplayer.hls.HlsMediaSource; import androidx.media3.exoplayer.source.MediaSource; import com.hik.netsdk.SimpleDemo.R; import com.hik.netsdk.SimpleDemo.View.DevMgtUI.AddDevActivity; import com.videogo.openapi.EZConstants; import com.videogo.openapi.EZOpenSDK; import org.json.JSONException; import org.json.JSONObject; import java.io.IOException; import java.util.concurrent.TimeUnit; import okhttp3.MediaType; import okhttp3.OkHttpClient; import okhttp3.Request; import okhttp3.RequestBody; import okhttp3.Response; public class MainActivity extends AppCompatActivity implements SurfaceHolder.Callback { // ... 其他变量保持不变 ... // 播放器相关 (使用 AndroidX Media3) private ExoPlayer mExoPlayer; private String mPlaybackUrl; private final OkHttpClient mHttpClient = new OkHttpClient.Builder() .connectTimeout(15, TimeUnit.SECONDS) .readTimeout(15, TimeUnit.SECONDS) .build(); // 播放器状态监听器 private final Player.Listener mPlayerListener = new Player.Listener() { @Override public void onPlaybackStateChanged(int state) { switch (state) { case Player.STATE_READY: mProgressBar.setVisibility(View.GONE); Log.d("ExoPlayer", "播放准备就绪"); break; case Player.STATE_BUFFERING: mProgressBar.setVisibility(View.VISIBLE); Log.d("ExoPlayer", "缓冲中..."); break; case Player.STATE_ENDED: Log.d("ExoPlayer", "播放结束"); break; case Player.STATE_IDLE: Log.d("ExoPlayer", "空闲状态"); break; } } @Override public void onPlayerError(PlaybackException error) { Log.e("ExoPlayer", "播放错误: " + error.getMessage()); handleError("播放错误: " + error.getMessage(), -1); } }; // ... onCreate 和其他方法保持不变 ... private void initExoPlayer() { // 释放现有播放器 if (mExoPlayer != null) { mExoPlayer.release(); } // 创建新的播放器实例 (AndroidX Media3) mExoPlayer = new ExoPlayer.Builder(this).build(); mExoPlayer.addListener(mPlayerListener); mExoPlayer.setVideoSurfaceHolder(mSurfaceHolder); // 创建媒体源 DataSource.Factory dataSourceFactory = new DefaultHttpDataSource.Factory(); MediaSource mediaSource = new HlsMediaSource.Factory(dataSourceFactory) .createMediaSource(MediaItem.fromUri(Uri.parse(mPlaybackUrl))); // 准备播放 mExoPlayer.setMediaSource(mediaSource); mExoPlayer.prepare(); mExoPlayer.play(); // 相当于 setPlayWhenReady(true) mProgressBar.setVisibility(View.VISIBLE); Log.d("ExoPlayer", "播放器初始化完成,开始播放"); } // ... 其他方法保持不变 ... } ``` ### 关键修复点解释 1. **依赖更新**: - 移除了旧的 `com.google.android.exoplayer` 依赖 - 添加了新的 `androidx.media3` 依赖 2. **导入更新**: - 所有 ExoPlayer 相关导入替换为 `androidx.media3` 包 - 特别注意 `SimpleExoPlayer` 已被 `ExoPlayer` 替代 3. **播放器初始化**: ```java // 旧方式 mExoPlayer = new SimpleExoPlayer.Builder(this).build(); // 新方式 (AndroidX Media3) mExoPlayer = new ExoPlayer.Builder(this).build(); ``` 4. **播放控制**: ```java // 旧方式 mExoPlayer.setPlayWhenReady(true); // 新方式 mExoPlayer.play(); ``` 5. **错误处理**: - `PlaybackException` 现在位于 `androidx.media3.common.PlaybackException` ### 常见问题解决 1. **如果仍然出现 "Cannot resolve symbol"**: - 执行 File > Invalidate Caches / Restart - 确保 Gradle 同步完成(View > Tool Windows > Gradle) 2. **兼容性问题**: ```groovy // 在 android 块中添加 compileOptions { sourceCompatibility JavaVersion.VERSION_1_8 targetCompatibility JavaVersion.VERSION_1_8 } ``` 3. **依赖冲突解决**: ```groovy configurations.all { resolutionStrategy { // 强制使用特定版本 force 'androidx.annotation:annotation:1.7.0' force 'androidx.core:core:1.12.0' } } ``` ### AndroidX Media3 的优势 1. **官方支持**:Google 官方维护的媒体播放库 2. **统一架构**:整合了 ExoPlayer 和其他媒体组件 3. **现代 API**:更简洁、更一致的 API 设计 4. **长期支持**:持续更新和维护 5. **更好的性能**:优化了内存管理和播放性能
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