安卓即使增加了权限也不可以访问网络

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.marivn_android_test_http"
    android:versionCode="1"
    android:versionName="1.0" >

    

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
    
	<uses-sdk
        android:minSdkVersion="8"
        android:targetSdkVersion="21" />
    <!-- 添加访问网络的授权 -->
	<uses-permission android:name="android.permission.INTERNET"></uses-permission>
</manifest>

删掉

android:targetSdkVersion="21"

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.marivn_android_test_http"
    android:versionCode="1"
    android:versionName="1.0" >

    

    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
    </application>
    
	<uses-sdk
        android:minSdkVersion="8"/>
    <!-- 添加访问网络的授权 -->
	<uses-permission android:name="android.permission.INTERNET"></uses-permission>
</manifest>