AsyncHttpClient来完成网页源代码的显示功能,json数据在服务器端的读取还有安卓上的读取

一、使用AsyncHttpClient来完成网页源代码的显示功能：

首先。我们引入

步骤：

1.添加网络权限

2.判断网页地址是否为空

3.不为空的情况下创建客户端对象

4.处理get/post请求

5.如果成功的话，设置显示内容的值

a) 获取文件响应编码类型（保证不乱码）

i. 遍历头部信息取出contentType_value的值

ii. 定义服务器缺省编码方式

iii.  处理contentType_value来获取编码方式

1. contentType_value是否有“=”

2. contentType_value是否为空

b) 根据服务端返回的编码给显示内容设置值

[java] view plaincopy

1. package com.example.android_htmlcode;  
2.   
3. import java.io.UnsupportedEncodingException;  
4.   
5. import org.apache.http.Header;  
6.   
7. import android.app.Activity;  
8. import android.os.Bundle;  
9. import android.text.TextUtils;  
10. import android.view.View;  
11. import android.widget.EditText;  
12. import android.widget.TextView;  
13. import android.widget.Toast;  
14.   
15. import com.loopj.android.http.AsyncHttpClient;  
16. import com.loopj.android.http.AsyncHttpResponseHandler;  
17.   
18. public class MainActivity extends Activity {  
19.   
20.     private EditText et_url;  
21.     private TextView tv_url;  
22.   
23.     @Override  
24.     protected void onCreate(Bundle savedInstanceState) {  
25.         super.onCreate(savedInstanceState);  
26.         // 设置显示视图  
27.         setContentView(R.layout.activity_main);  
28.         et_url = (EditText) findViewById(R.id.et_url);  
29.         tv_url = (TextView) findViewById(R.id.tv_info);  
30.     }  
31.   
32.     // android:onClick="sendHttpUil  
33.     public void sendHttpUil(View v) {  
34.         int id = v.getId();  
35.         switch (id) {  
36.         case R.id.btn_send:  
37.   
38.             String url = et_url.getText().toString();  
39.             // 判断网页地址是否为空  
40.             if (TextUtils.isEmpty(url)) {  
41.                 Toast.makeText(this, "网页地址不能为空", 0).show();  
42.             } else {  
43.                 // 创建客户端对象  
44.                 AsyncHttpClient client = new AsyncHttpClient();  
45.   
46.                 // 处理get/post请求  
47.                 client.get(url, new AsyncHttpResponseHandler() {  
48.   
49.                     @Override  
50.                     public void onSuccess(int statusCode, Header[] headers,  
51.                             byte[] responseBody) {  
52.                         super.onSuccess(statusCode, headers, responseBody);  
53.                         // 获取文件响应类型  
54.                         String contentType_value = null;  
55.   
56.                         // 遍历头部信息  
57.                         for (Header header : headers) {  
58.                             // 获取contentType_value的头部信息  
59.                             if (header.getName().equals("Content-Type")) {  
60.                                 // 获取他的value值  
61.                                 contentType_value = header.getValue();  
62.                             }  
63.                         }  
64.   
65.                         // 定义服务器端缺省的编码方式  
66.                         String default_charset = "UTF-8";  
67.                         // 处理contentType_value来获取编码方式  
68.                         // 判断是否为null  
69.                         if (contentType_value != null) {  
70.                             // 判断是否有=字符  
71.                             if (contentType_value.contains("=")) {  
72.                                 // 获取=字符位置  
73.                                 int index = contentType_value.indexOf("=");  
74.                                 // 从=所在位置的下一个字符开始截取，返回服务器端的编码  
75.                                 default_charset = contentType_value.substring(  
76.                                         index + 1, contentType_value.length());  
77.                             } else {  
78.                                 String result = new String(responseBody);  
79.                                 default_charset = getCharSet(result);  
80.                             }  
81.                         } else {  
82.                             String result = new String(responseBody);  
83.                             default_charset = getCharSet(result);  
84.                         }  
85.                         Toast.makeText(MainActivity.this,  
86.                                 "编码是：" + default_charset, 0).show();  
87.   
88.                         if (statusCode == 200) {  
89.                             try {  
90.                                 tv_url.setText(new String(responseBody,  
91.                                         default_charset));  
92.                             } catch (UnsupportedEncodingException e) {  
93.                                 // TODO Auto-generated catch block  
94.                                 e.printStackTrace();  
95.                             }  
96.                         }  
97.                     }  
98.   
99.                     /** 
100.                      * 获取网页源代码中默认的编码 
101.                      *  
102.                      * @param result 
103.                      * @return 
104.                      */  
105.                     public String getCharSet(String result) {  
106.                         String defaultCharset = null;  
107.                         // <mate http-equiv="Content-Type"  
108.                         // content="text/html; charset=GBK" /> //html4  
109.                         // <mate charset="UTF-8">  
110.                         if (result != null) {  
111.                             if (result  
112.                                     .contains("content=\"text/html; charset=GBK\"")) {  
113.                                 defaultCharset = "GBK";  
114.                             } else if (result  
115.                                     .contains("content=\"text/html; charset=UTF-8\"")) {  
116.                                 defaultCharset = "UTF-8";  
117.                             } else if (result  
118.                                     .contains("content=\"text/html; charset=GB2312\"")) {  
119.                                 defaultCharset = "GB2312";  
120.                             } else if (result.contains("charset=\"UTF-8\"")) {  
121.                                 defaultCharset = "UTF-8";  
122.                             } else if (result.contains("charset=\"UTF-8\"")) {  
123.                                 defaultCharset = "GBK";  
124.                             }  
125.                         }  
126.                         return defaultCharset;  
127.                     }  
128.   
129.                 });  
130.             }  
131.   
132.             break;  
133.   
134.         default:  
135.             break;  
136.         }  
137.     }  
138.   
139. }  

二、通过开源框架获取JSON数据：

[java] view plaincopy

1. package com.example.android_json;  
2.   
3. import org.apache.http.Header;  
4. import org.json.JSONArray;  
5. import org.json.JSONException;  
6. import org.json.JSONObject;  
7.   
8. import com.loopj.android.http.AsyncHttpClient;  
9. import com.loopj.android.http.JsonHttpResponseHandler;  
10.   
11. import android.os.Bundle;  
12. import android.app.Activity;  
13. import android.view.Menu;  
14. import android.widget.Toast;  
15.   
16. public class MainActivity extends Activity {  
17.   
18.     @Override  
19.     protected void onCreate(Bundle savedInstanceState) {  
20.         super.onCreate(savedInstanceState);  
21.         setContentView(R.layout.activity_main);  
22.         // http://172.16.237.200:8080/video/JsonServlet  
23.         initData();  
24.     }  
25.   
26.     private void initData() {  
27.         // 创建客户端对象  
28.         AsyncHttpClient client = new AsyncHttpClient();  
29.         String url = "http://172.16.237.200:8080/video/JsonServlet";  
30.         Toast.makeText(this, "发送请求到服务器", 0).show();  
31.         client.get(url, new JsonHttpResponseHandler() {  
32.               
33.             //返回JSONObject对象|JSONOArray对象  
34.             @Override  
35.             public void onSuccess(int statusCode, Header[] headers,  
36.                     JSONArray response) {  
37.                 // TODO Auto-generated method stub  
38.                 super.onSuccess(statusCode, headers, response);  
39.   
40.                 if (statusCode == 200) {  
41.                     //遍历json数组  
42.                     for (int i = 0; i < response.length(); i++) {  
43.                         try {  
44.                             // 获取具体的一个JSONObject对象  
45.                             JSONObject obj = response.getJSONObject(i);  
46.                             //JSONObject对象get(“属性名”)，getString(“属性名”),getInt(“属性名”)等方法来获取指定属性名的值  
47.                             System.out.println("序号" + obj.getString("id")  
48.                                     + "--------姓名：" + obj.getString("name")  
49.                                     + "--------密码：" + obj.getString("pass")  
50.                             + "--------其他：" + obj.getString("pass"));  
51.                         } catch (JSONException e) {  
52.                             // TODO Auto-generated catch block  
53.                             e.printStackTrace();  
54.                         }  
55.                     }  
56.                 }  
57.             }  
58.         });  
59.     }  
60.   
61. }  

常见错误分析：当遍历json数组时，若没有对于json数据就会报错，例如：（部分代码整理源于赵雅智女士的）