jackson和httpcliet-优快云博客

本文链接：https://blog.youkuaiyun.com/qq_41683274/article/details/82720761

webservice->xml

jackson->json

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
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
3. 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<NameValuePair> params = new ArrayList<NameValuePair>();
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?)”
       <uses-permission android:name="android.permission.INTERNET" />

  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
4. 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

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;
}
}

//增
private void add() {
Log.i(“test”, “add…”);
HttpClientPost post = new HttpClientPost(“/jsp/userAction.action”);
post.addParam(“methodName”,”userAdd”);
post.addParam(“uid”,”003”);
post.addParam(“uname”,”嗨咯”);
post.addParam(“upwd”,”123456”);
post.addParam(“Menuid”,”112”);
```
post.submit(new HttpClientPost.Callback() {
    @Override
    public void execute(String json) {
        Log.i("server4",json);
    }
});
```
}

//改
private void edit() {
```
Log.i("test", "edit...");
HttpClientPost post = new HttpClientPost("/jsp/userAction.action");
post.addParam("methodName","userUpdate");
post.addParam("SerialNo","3");
post.addParam("uid","003");
post.addParam("uname","王五123");
post.addParam("upwd","123456");
post.submit(new HttpClientPost.Callback() {
    @Override
    public void execute(String json) {
        Log.i("server22",json);
    }
});
```
}
//删
private void del() {
Log.i(“test”, “del…”);
HttpClientPost post = new HttpClientPost(“/jsp/userAction.action”);
post.addParam(“methodName”,”userDelete”);
post.addParam(“SerialNo”,”003”);
post.submit(new HttpClientPost.Callback() {
@Override
public void execute(String json) {
Log.i(“server3”,json);
}
});

}

//查单个
private void load() {
Log.i(“test”, “load…”);
HttpClientPost post = new HttpClientPost(“/jsp/userAction.action”);
post.addParam(“methodName”,”userList”);
post.addParam(“uname”,”嗨咯”);
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();
}
}
});
}

//查询所有
private void list() {
Log.i(“test”, “list…”);
HttpClientPost post = new HttpClientPost(“/jsp/userAction.action”);
post.addParam(“methodName”,”userList”);
post.submit(new HttpClientPost.Callback() {
@Override
public void execute(String json) {
Log.i(“server5”,json);
}
});
}
}