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package com.ccl.getp_w_picpath;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.text.TextUtils;
import android.view.View;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.Toast;
public class MainActivity extends Activity {
private EditText et_path;
private ImageView iv;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
et_path = (EditText) findViewById(R.id.et_path);
iv = (ImageView) findViewById(R.id.iv);
}
public void getImage(View view){
String path = et_path.getText().toString().trim();
if(TextUtils.isEmpty(path)){
Toast.makeText(this, "地址不能為空", 0).show();
return;
}
try {
URL url = new URL(path);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setConnectTimeout(5000);
System.out.println("響應碼是--"+conn.getResponseCode());
if(conn.getResponseCode()==200){
//獲取服務器返回的流數據
InputStream in = conn.getInputStream();
//將返回的流數據解析成圖片
Bitmap bitmap = BitmapFactory.decodeStream(in);
//顯示圖片
iv.setImageBitmap(bitmap);
in.close();
}
} catch (Exception e) {
e.printStackTrace();
}
}
}Android模擬器版本4.1.2
異常解釋:在主線程中的網絡異常
原因:Android2.3版本后不允許在主線程中直接請求網絡獲取數據
解決方法（兩種）：
一：onCreate方法中加入如下代碼（不推薦使用,有可能阻塞Android主線程)
if (android.os.Build.VERSION.SDK_INT > 9) {
StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder().permitAll().build();
StrictMode.setThreadPolicy(policy);
}二：使用Android 的handler機制，另外開啟一個子線程請求網絡獲取數據(推薦使用)
package com.ccl.getp_w_picpath;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.text.TextUtils;
import android.view.View;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.Toast;
public class MainActivity extends Activity {
private EditText et_path;
private ImageView iv;
private String path;
//使用Handler更新主線程（UI線程)
private Handler handler = new Handler(){
public void handleMessage(Message msg) {
Bitmap bitmap = (Bitmap) msg.obj;
iv.setImageBitmap(bitmap);
};
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
et_path = (EditText) findViewById(R.id.et_path);
iv = (ImageView) findViewById(R.id.iv);
}
public void getImage(View view){
path = et_path.getText().toString().trim();
if(TextUtils.isEmpty(path)){
Toast.makeText(this, "地址不能為空", 0).show();
return;
}
new Thread(){
public void run(){
try {
URL url = new URL(path);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setConnectTimeout(5000);
System.out.println("響應碼是--"+conn.getResponseCode());
if(conn.getResponseCode()==200){
//獲取服務器返回的流數據
InputStream in = conn.getInputStream();
//將返回的流數據解析成圖片
Bitmap bitmap = BitmapFactory.decodeStream(in);
//使用handler傳遞消息
Message msg = Message.obtain();
msg.obj = bitmap;//傳遞的數據
handler.sendMessage(msg);
in.close();
}
} catch (Exception e) {
e.printStackTrace();
}
}
}.start();
}
}注意兩點：
Message對象的創建使用obtain方法可以達到對象重用的目的,節省內存開銷。
Message對象可以使用msg.what = 傳遞消息的類型,handler可以根據傳遞的消息類型做不同處理，優化代碼如下：
package com.ccl.getp_w_picpath;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.text.TextUtils;
import android.view.View;
import android.widget.EditText;
import android.widget.ImageView;
import android.widget.Toast;
public class MainActivity extends Activity {
protected static final int SUCCESS = 0;
protected static final int ERROR = 1;
protected static final int NETWORK_ERROR = 2;
private EditText et_path;
private ImageView iv;
private String path;
//使用Handler更新主線程（UI線程)
private Handler handler = new Handler(){
public void handleMessage(Message msg) {
switch (msg.what) {
case SUCCESS:
Bitmap bitmap = (Bitmap) msg.obj;
iv.setImageBitmap(bitmap);
break;
case ERROR:
Toast.makeText(MainActivity.this, "獲取圖片失敗", 0).show();
break;
case NETWORK_ERROR:
Toast.makeText(MainActivity.this, "連接網絡失敗", 0).show();
break;
}
};
};
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
et_path = (EditText) findViewById(R.id.et_path);
iv = (ImageView) findViewById(R.id.iv);
}
public void getImage(View view){
path = et_path.getText().toString().trim();
if(TextUtils.isEmpty(path)){
Toast.makeText(this, "地址不能為空", 0).show();
return;
}
new Thread(){
public void run(){
try {
URL url = new URL(path);
HttpURLConnection conn = (HttpURLConnection) url.openConnection();
conn.setRequestMethod("GET");
conn.setConnectTimeout(5000);
System.out.println("響應碼是--"+conn.getResponseCode());
if(conn.getResponseCode()==200){
//獲取服務器返回的流數據
InputStream in = conn.getInputStream();
//將返回的流數據解析成圖片
Bitmap bitmap = BitmapFactory.decodeStream(in);
//使用handler傳遞消息
Message msg = Message.obtain();
msg.obj = bitmap;//傳遞的數據
msg.what = SUCCESS;//傳遞的消息類型,handler可根據消息類型做不同處理
handler.sendMessage(msg);
in.close();
}else{
Message msg = Message.obtain();
msg.what = ERROR;
handler.sendMessage(msg);
}
} catch (Exception e) {
Message msg = Message.obtain();
msg.what = NETWORK_ERROR;
handler.sendMessage(msg);
e.printStackTrace();
}
}
}.start();
}
}
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