Android从第三方项目获取数据通常使用这两种方式
1,xml格式的数据交互(对xml进行解析获取数据)
2,json格式的数据交互(对json格式数据进行解析,使用HttpClient技术访问后台代码)
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
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)。
Request sent数据请求时间;Waiting数据响应时间,
注:多注意Request sent和Waiting时间的长短,如这两种时间超时明显过长可能是第三方数据发生了地址性的变化
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);
下面我举一个实例来讲述Android与Java端的数据交互:
1.这里我使用一个已经封装好的HttpClient对象Post请求
package com.example.jack_and06; 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://192.168.43.157:8080/blog_limit/"; // 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) { /** * 调用类对象excute()方法属性 */ 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(); } //创建内部回调函数,使用二十三种设计模式之策略模式 、 //(作用:在方法或类中已经完成了对应的功能,然后在调用方根据自己的需求去处理结果) public static interface Callback { void execute(String json); } }
2.创建一个Android布局
<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:app="http://schemas.android.com/apk/res-auto" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical" tools:context=".MainActivity"> <Button android:id="@+id/bt_main_add" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="新增" /> <Button android:id="@+id/bt_main_edit" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="修改" /> <Button android:id="@+id/bt_main_del" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="删除" /> <Button android:id="@+id/bt_main_load" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="查单个" /> <Button android:id="@+id/bt_main_list" android:layout_width="match_parent" android:layout_height="wrap_content" android:text="查全部" /> </LinearLayout>
3.在Activity类中实现数据的交互
package com.example.jack_and06; 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.List; 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..."); } private void edit() { Log.i("test", "edit..."); } private void del() { Log.i("test", "del..."); } private void load() { Log.i("test", "load..."); } private void list() { Log.i("test", "list..."); //创建httpClientPost对象输入数据路径 HttpClientPost httpClientPost = new HttpClientPost("userAction.action"); httpClientPost.addParam("methodName","blogUserList"); httpClientPost.submit(new HttpClientPost.Callback() { @Override public void execute(String json) { Log.i("json",json);//LogCat输出数据 ObjectMapper om = new ObjectMapper(); try { Map<String,Object> map = om.readValue(json, Map.class); List rows = (List) map.get("rows"); Map<String,Object> o = (Map<String, Object>) rows.get(0); Log.i("username",o.get("username").toString()); } catch (IOException e) { e.printStackTrace(); } } }); } }
最后我们使用模拟器来查看所查询到的Java数据
Android应用在LogCat输出数据信息