jackson和httpcliet

最新推荐文章于 2024-09-13 13:24:14 发布

Zhang_0220

最新推荐文章于 2024-09-13 13:24:14 发布

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分类专栏： Android

本文链接：https://blog.youkuaiyun.com/x_b_z123/article/details/82728464

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本文详细介绍Android应用如何通过HttpClient调用Java后端接口，包括创建HttpClient对象、发送POST请求、处理响应数据及JSON解析。同时，提供了具体的代码示例和步骤说明。

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1. 接口

1.1 OOP interface
1.2 url
json

2. 如何给前端开发人提供接口

2.1 提供地址/参数/返回值(json)

2.2 *.jar

http://192.168.43.37:8080/T212_easyui/jsp/userAction.action?methodName=userList

http://localhost:8080/T212_easyui/jsp/userAction.action?methodName=userUpdate
SerialNo: 1
uid: 001
uname: 张三1
upwd: 123456

凡是手机没有访问到，接受不到数据，后面的开发都没用

核心内容（Android调用Java，完成查询单个以及修改的功能）

1、准备一个Java端的程序
2、通过httpclient调用Java端数据

//创建HttpClientPost类
package com.example.a0914_a07;

import java.io.Serializable;
import java.util.ArrayList;
import java.util.List;

import org.apache.http.HttpEntity;
import org.apache.http.HttpResponse;
import org.apache.http.NameValuePair;
import org.apache.http.client.HttpClient;
import org.apache.http.client.entity.UrlEncodedFormEntity;
import org.apache.http.client.methods.HttpPost;
import org.apache.http.impl.client.DefaultHttpClient;
import org.apache.http.message.BasicNameValuePair;
import org.apache.http.params.CoreConnectionPNames;
import org.apache.http.util.EntityUtils;

import android.os.AsyncTask;

/**
 * 封装 HttpClient对象POST请求
 *
 */
public class HttpClientPost implements Serializable {

    private static final long serialVersionUID = 1777547416049652217L;

    private static HttpClient httpClient = new DefaultHttpClient();

    static {
        httpClient.getParams().setParameter(
                CoreConnectionPNames.CONNECTION_TIMEOUT, 2000);// 连接时间
        httpClient.getParams().setParameter(CoreConnectionPNames.SO_TIMEOUT,
                3000);// 数据传输时间
    }

    // 字符集
    private static String encoding = "UTF-8";

    // 服务器地址+端口号+项目名
    private static String basePath = "http://192.168.43.103:8080/0820_easyui";

    // 子控制器的路径
    private String path;

    // 保存请求中的参数
    private List<NameValuePair> params = new ArrayList<NameValuePair>();;

    public HttpClientPost(String path) {
        super();
        this.path = path;
    }

    /**
     * 向POST请求中添加参数
     *
     * @param name
     * @param value
     */
    public void addParam(String name, String value) {
        if (value == null) {
            params.add(new BasicNameValuePair(name, ""));
        } else {
            params.add(new BasicNameValuePair(name, value));
        }
    }

    /**
     * 提交POST请求
     */
    @SuppressWarnings("unchecked")
    public void submit(final HttpClientPost.Callback callback) {
        new AsyncTask() {
            private String json;

            @Override
            protected Object doInBackground(Object... args) {
                try {
                    // 1. 创建HttpClient对象

                    // 2. 创建HttpGet(或HttpPost)对象
                    HttpPost httpPost = new HttpPost(basePath + path);

                    // 3. 向POST请求中添加参数(可选)
                    if (0 != params.size()) {
                        HttpEntity paramEntity = new UrlEncodedFormEntity(
                                params, encoding);
                        httpPost.setEntity(paramEntity);
                    }

                    // 4. 发送POST请求，并获得响应
                    HttpResponse httpResponse = httpClient.execute(httpPost);

                    // 5. 处理响应
                    if (200 == httpResponse.getStatusLine().getStatusCode()) {
                        HttpEntity responseEntity = httpResponse.getEntity();// 此对象包含服务器的响应内容
                        this.json = EntityUtils.toString(responseEntity);
                    }
                } catch (Exception e) {
                    throw new RuntimeException(e);
                }
                return null;
            }

            protected void onPostExecute(Object result) {
                callback.execute(this.json);
            }

        }.execute();
    }

    public static interface Callback {
        void execute(String json);
    }
}

3、将json串转成对象

package com.example.a0914_a07;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.View;
import android.widget.Button;

import com.fasterxml.jackson.databind.ObjectMapper;

import java.io.IOException;
import java.util.Map;

public class MainActivity extends AppCompatActivity implements View.OnClickListener {

    private Button bt_main_add;
    private Button bt_main_edit;
    private Button bt_main_del;
    private Button bt_main_load;
    private Button bt_main_list;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        //查找控件
        findViews();

        //绑定监听器
        bt_main_add.setOnClickListener(this);
        bt_main_edit.setOnClickListener(this);
        bt_main_del.setOnClickListener(this);
        bt_main_load.setOnClickListener(this);
        bt_main_list.setOnClickListener(this);

    }

    private void findViews() {
        bt_main_add = (Button) findViewById(R.id.bt_main_add);
        bt_main_edit = (Button) findViewById(R.id.bt_main_edit);
        bt_main_del = (Button) findViewById(R.id.bt_main_del);
        bt_main_load = (Button) findViewById(R.id.bt_main_load);
        bt_main_list = (Button) findViewById(R.id.bt_main_list);
    }


    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.bt_main_add:
                add();
                break;
            case R.id.bt_main_edit:
                edit();
                break;
            case R.id.bt_main_del:
                del();
                break;
            case R.id.bt_main_load:
                load();
                break;
            case R.id.bt_main_list:
                list();
                break;
        }
    }

    private void add() {
        Log.i("test", "add...");
        HttpClientPost post=new HttpClientPost("/jsp/userAction.action");
        post.addParam("methodName","userAdd");
        post.addParam("uname","张三");
        post.addParam("SerialNo","1");
        post.addParam("uid","001");
        post.addParam("upwd","123456");
        post.submit(new HttpClientPost.Callback() {
            @Override
            public void execute(String json) {
                Log.i("server44:",json);
            }
        });
    }

    private void edit() {
        Log.i("test", "edit...");
        HttpClientPost post=new HttpClientPost("/jsp/userAction.action");
        post.addParam("methodName","userUpdate");
        post.addParam("uname","张三333");
        post.addParam("SerialNo","1");
        post.addParam("uid","001");
        post.addParam("upwd","123456");
        post.submit(new HttpClientPost.Callback() {
            @Override
            public void execute(String json) {
                Log.i("server22:",json);
            }
        });
    }

    private void del() {
        Log.i("test", "del...");
        HttpClientPost post=new HttpClientPost("/jsp/userAction.action");
        post.addParam("methodName","userDelete");
        post.addParam("SerialNo","1");
        post.submit(new HttpClientPost.Callback() {
            @Override
            public void execute(String json) {
                Log.i("server33:",json);
            }
        });
    }

    private void load() {
        Log.i("test", "load...");
        HttpClientPost post=new HttpClientPost("/jsp/userAction.action");
        post.addParam("methodName","userList");
        post.addParam("uname","张三");
        post.submit(new HttpClientPost.Callback() {
            @Override
            public void execute(String json) {
                Log.i("server:",json);
                ObjectMapper om=new ObjectMapper();
                try {
                    Map map = om.readValue(json, Map.class);
                    Log.i("server:",map.get("total").toString());
                    Log.i("server:",map.get("rows").getClass().getName());
                } catch (IOException e) {
                    e.printStackTrace();
                }
            }
        });
    }

    private void list() {
        Log.i("test", "list...");
    }
}

webservice->xml

jackson->json

1. jackson

1.1 Java->Json
1.1.1 ObjectMap
1.1.2 JsonGenerator
1.1.3 @JsonIgnore
hibernate中一对多、多对多双向关联会出现这种死循环

2. 简介

2.1 HttpClient是Apache Jakarta Common下的子项目，用来提供高效的、最新的、
功能丰富的支持HTTP协议的客户端编程工具包，并且它支持HTTP协议最新的版本和协议。
2.2 Android已成功集成了HttpClient，这意味这开发人员可以直接在Android应用中使用
HtppClient来提交请求、接收响应

  注：在API 23中，Google已经移除了移除了Apache HttpClient相关的类 ，
  在build.gradle中的android {}中加上useLibrary 'org.apache.http.legacy'，
  详情见资料“”

案例一：HttpClient的使用步骤

HttpClient的使用步骤
3.1 创建HttpClient对象
HttpClient httpClient = new DefaultHttpClient();

3.2 创建HttpGet(或HttpPost)对象
HttpGet HttpGet = new HttpGet(“http://www.baidu.com“);
HttpPost httpPost = new HttpPost(“http://www.baidu.com“);

3.3 添加参数(可选)
setParams(HttpParams params)//HttpGet和HttpPost共有
setEntity(HttpEntity entity)//HttpPost独有

List params = new ArrayList();
params.add(new BasicNameValuePair(“age”, “20”));
params.add(new BasicNameValuePair(“like”, “aa”));
params.add(new BasicNameValuePair(“like”, “bb”));
params.add(new BasicNameValuePair(“like”, “cc”));
params.add(new BasicNameValuePair(“newsCategoryId”, “1”));
HttpEntity paramEntity = new UrlEncodedFormEntity(params,”UTF-8”);
httpPost.setEntity(paramEntity);

3.4 发送GET(或POST)请求，并获得响应
HttpResponse httpResponse = httpClient.execute(HttpUriRequest request);

注1：HttpUriRequest为HttpGet和HttpPost的父类
注2：需要添加允许网络访问权限，不然会报错“java.lang.SecurityException: Permission denied (missing INTERNET permission?)”

注3：如果地址错误，或服务器未开户，HttpClient这SB会等待N久(>24小时)。
所以请记得设置超时时间，所以请记得设置超时时间，所以请记得设置超时时间
所以请记得设置超时时间，所以请记得设置超时时间，所以请记得设置超时时间
所以请记得设置超时时间，所以请记得设置超时时间，所以请记得设置超时时间
```
   另外HttpClient版本不一样，代码也不一样。下面的4.0版本的写法
   httpClient.getParams().setParameter(CoreConnectionPNames.CONNECTION_TIMEOUT, 2000);// 连接时间
   httpClient.getParams().setParameter(CoreConnectionPNames.SO_TIMEOUT, 2000);// 数据传输时间
```
3.5 处理响应
3.5.1 响应状态码(200)
httpResponse.getStatusLine().getStatusCode()

3.5.2 响应头
getAllHeaders()/getHeaders(String name)

3.5.3 响应内容
HttpEntity httpEntity = httpResponse.getEntity();//此对象包含服务器的响应内容
String result = EntityUtils.toString(httpEntity);

案例二：使用HttpClientUtils与服务器通信

Android客户端与服务器通信
4.1 JSON数据交换
android系统内置了对象json的支持，另外json其实就以下几个对象的使用：
JSONObject、JSONArray、JSONStringer、JSONException
4.2 web service，底层使用xml交换数据
关于org.apache.http.conn.HttpHostConnectException: Connection to refused错误的解决办法
增加网络访问权限：
找到 AndroidManifest.xml 文件。在application标签后面加上
检查ip地址：
启动的android模拟器吧自己也当成127.0.0.1和localhost，如果使用了localhost或者127.0.0.1则会被拒绝访问，
把ip地址改成实际地址，如：192.168.1.5