android学习之选择媒体库中的图片

从媒体库中选择图片

主要是启动系统相关Activity

Intent i = new Intent( Intent.ACTION_PICK,

android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI;

startActivityForResult(i, RESULT_LOAD_IMAGE);

注意：这里要传一个整形的常量RESULT_LOAD_IMAGE到

startActivityForResult()

方法。

一旦用户选择了一张图片，onActivityResult()方法将会被调用。我们需要处理这个方法得到的数据。onActivityResult()方法只有当图片被选中后才会调用。在这个方法中，我们需要检查requestCode是否是我们之前传给startActivityForResult()方法的RESULT_LOAD_IMAGE。

Java代码：

[java] view
plaincopy

package com.example.com.njupt.zhb.selectimages;

import android.app.Activity;

import android.content.Intent;

import android.database.Cursor;

import android.graphics.BitmapFactory;

import android.net.Uri;

import android.os.Bundle;

import android.provider.MediaStore;

import android.view.Menu;

import android.view.View;

import android.widget.Button;

import android.widget.ImageView;

public class MainActivity extends Activity {

private static int RESULT_LOAD_IMAGE = 123;

private ImageView imageView;

private String picturePath=null;

@Override

public void onCreate(Bundle savedInstanceState) {

super.onCreate(savedInstanceState);

setContentView(R.layout.activity_main);

imageView = (ImageView) findViewById(R.id.imgView);

Button buttonLoadImage = (Button) findViewById(R.id.buttonLoadPicture);

buttonLoadImage.setOnClickListener(new View.OnClickListener() {

@Override

public void onClick(View arg0) {

Intent i = new Intent(

Intent.ACTION_PICK,

android.provider.MediaStore.Images.Media.EXTERNAL_CONTENT_URI);

startActivityForResult(i, RESULT_LOAD_IMAGE);

}

});

}

@Override

protected void onActivityResult(int requestCode, int resultCode, Intent data) {

super.onActivityResult(requestCode, resultCode, data);

if (requestCode == RESULT_LOAD_IMAGE && resultCode == RESULT_OK && null != data) {

Uri selectedImage = data.getData();

String[] filePathColumn = { MediaStore.Images.Media.DATA };

Cursor cursor = getContentResolver().query(selectedImage,

filePathColumn, null, null, null);

cursor.moveToFirst();

int columnIndex = cursor.getColumnIndex(filePathColumn[0]);

picturePath = cursor.getString(columnIndex);

cursor.close();

imageView.setImageBitmap(BitmapFactory.decodeFile(picturePath));

}

}

@Override

public boolean onCreateOptionsMenu(Menu menu) {

getMenuInflater().inflate(R.menu.activity_main, menu);

return true;

}

}

XML布局文件

[html] view
plaincopy

<?xml version="1.0" encoding="utf-8"?>

<AbsoluteLayout

android:id="@+id/widget0"

android:layout_width="fill_parent"

android:layout_height="fill_parent"

xmlns:android="http://schemas.android.com/apk/res/android">

<ImageView

android:id="@+id/imgView"

android:layout_width="315dp"

android:layout_height="384dp"

android:layout_x="2dp"

android:layout_y="4dp" />

<Button

android:id="@+id/buttonLoadPicture"

android:layout_width="317dp"

android:layout_height="wrap_content"

android:text="SelectImage"

android:layout_x="2dp"

android:layout_y="391dp" />

</AbsoluteLayout>