Android核心基础-7.Android 网络通信-1.获取文本数据

一、获取文本数据

<uses-permission android:name="android.permission.INTERNET" />

1.1网络请求

public class TextService {

public String getText(String path) throws Exception {
URL url = new URL(path);                                                // 把路径封装成URL对象
HttpURLConnection conn = (HttpURLConnection) url.openConnection();      // 打开连接对象(还未联网)
conn.setConnectTimeout(5000);                   // 设置超时时间, 如果连接超过5000毫秒未响应, 就抛出异常

int code = conn.getResponseCode();              // 获取响应码(真正联网)
if (code == 200) {                              // 如果成功
InputStream in = conn.getInputStream();     // 获取输入流
ByteArrayOutputStream out = new ByteArrayOutputStream();    // 可以写出数据到内存的输出流
byte[] buffer = new byte[8192];
int length;
while ((length = in.read(buffer)) != -1)    // 从网络读取数据
out.write(buffer, 0, length);           // 向内存写出数据
in.close();
out.close();
conn.disconnect();

byte[] data = out.toByteArray();    // 把写到内存的数据读取出来
String text = new String(data);     // 解码为字符串(默认UTF-8)
return text;
}

conn.disconnect();
throw new NetworkErrorException("网络错误: " + code);
}
}

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".ClassicActivity" >

<Button
android:id="@+id/bt"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentRight="true"
android:onClick="go"
android:text="GO" />

<EditText
android:id="@+id/et"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_alignBaseline="@id/bt"
android:layout_toLeftOf="@id/bt"
android:hint="请输入要访问的地址"
android:inputType="textUri" />

<TextView
android:id="@+id/tv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_below="@id/et" />

</RelativeLayout>

public class MainActivity extends Activity {

private EditText et;
private TextView tv;
private TextService service;
private Handler handler = new Handler();

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

et = (EditText) findViewById(R.id.et);
tv = (TextView) findViewById(R.id.tv);
service = new TextService();
}

public void go(View v) {
new Thread() {
public void run() {
try {
String path = et.getText().toString().trim();   // 从EditText获取地址
final String text = service.getText(path);      // 访问网络, 得到文本
handler.post(new Runnable() {
public void run() {
tv.setText(text);                       // 设置到TextView中
}
});
} catch (Exception e) {
e.printStackTrace();
handler.post(new Runnable(){
public void run() {
Toast.makeText(getApplicationContext(), "服务器忙, 请稍后再试!", Toast.LENGTH_SHORT).show();
}
});
}
}
}.start();
}
}