安卓实训第六天：首先使用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

package com.example.android_htmlcode;import java.io.UnsupportedEncodingException;import org.apache.http.Header;import android.app.Activity;import android.os.Bundle;import android.text.TextUtils;import android.view.View;import android.widget.EditText;import android.widget.TextView;import android.widget.Toast;import com.loopj.android.http.AsyncHttpClient;import com.loopj.android.http.AsyncHttpResponseHandler;public class MainActivity extends Activity {private EditText et_url;private TextView tv_url;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);// 设置显示视图setContentView(R.layout.activity_main);et_url = (EditText) findViewById(R.id.et_url);tv_url = (TextView) findViewById(R.id.tv_info);}// android:onClick="sendHttpUilpublic void sendHttpUil(View v) {int id = v.getId();switch (id) {case R.id.btn_send:String url = et_url.getText().toString();// 判断网页地址是否为空if (TextUtils.isEmpty(url)) {Toast.makeText(this, "网页地址不能为空", 0).show();} else {// 创建客户端对象AsyncHttpClient client = new AsyncHttpClient();// 处理get/post请求client.get(url, new AsyncHttpResponseHandler() {@Overridepublic void onSuccess(int statusCode, Header[] headers,byte[] responseBody) {super.onSuccess(statusCode, headers, responseBody);// 获取文件响应类型String contentType_value = null;// 遍历头部信息for (Header header : headers) {// 获取contentType_value的头部信息if (header.getName().equals("Content-Type")) {// 获取他的value值contentType_value = header.getValue();}}// 定义服务器端缺省的编码方式String default_charset = "UTF-8";// 处理contentType_value来获取编码方式// 判断是否为nullif (contentType_value != null) {// 判断是否有=字符if (contentType_value.contains("=")) {// 获取=字符位置int index = contentType_value.indexOf("=");// 从=所在位置的下一个字符开始截取，返回服务器端的编码default_charset = contentType_value.substring(index + 1, contentType_value.length());} else {String result = new String(responseBody);default_charset = getCharSet(result);}} else {String result = new String(responseBody);default_charset = getCharSet(result);}Toast.makeText(MainActivity.this,"编码是：" + default_charset, 0).show();if (statusCode == 200) {try {tv_url.setText(new String(responseBody,default_charset));} catch (UnsupportedEncodingException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}/** * 获取网页源代码中默认的编码 *  * @param result * @return */public String getCharSet(String result) {String defaultCharset = null;// <mate http-equiv="Content-Type"// content="text/html; charset=GBK" /> //html4// <mate charset="UTF-8">if (result != null) {if (result.contains("content=\"text/html; charset=GBK\"")) {defaultCharset = "GBK";} else if (result.contains("content=\"text/html; charset=UTF-8\"")) {defaultCharset = "UTF-8";} else if (result.contains("content=\"text/html; charset=GB2312\"")) {defaultCharset = "GB2312";} else if (result.contains("charset=\"UTF-8\"")) {defaultCharset = "UTF-8";} else if (result.contains("charset=\"UTF-8\"")) {defaultCharset = "GBK";}}return defaultCharset;}});}break;default:break;}}}

 

二、通过开源框架获取JSON数据：

package com.example.android_json;import org.apache.http.Header;import org.json.JSONArray;import org.json.JSONException;import org.json.JSONObject;import com.loopj.android.http.AsyncHttpClient;import com.loopj.android.http.JsonHttpResponseHandler;import android.os.Bundle;import android.app.Activity;import android.view.Menu;import android.widget.Toast;public class MainActivity extends Activity {@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);// http://172.16.237.200:8080/video/JsonServletinitData();}private void initData() {// 创建客户端对象AsyncHttpClient client = new AsyncHttpClient();String url = "http://172.16.237.200:8080/video/JsonServlet";Toast.makeText(this, "发送请求到服务器", 0).show();client.get(url, new JsonHttpResponseHandler() {//返回JSONObject对象|JSONOArray对象@Overridepublic void onSuccess(int statusCode, Header[] headers,JSONArray response) {// TODO Auto-generated method stubsuper.onSuccess(statusCode, headers, response);if (statusCode == 200) {//遍历json数组for (int i = 0; i < response.length(); i++) {try {// 获取具体的一个JSONObject对象JSONObject obj = response.getJSONObject(i);//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System.out.println("序号" + obj.getString("id")+ "--------姓名：" + obj.getString("name")+ "--------密码：" + obj.getString("pass")+ "--------其他：" + obj.getString("pass"));} catch (JSONException e) {// TODO Auto-generated catch blocke.printStackTrace();}}}}});}}

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）