Android中调用另一个Activity并返回结果-以模拟选择头像功能为例

不念不忘少年蓝@ 2023-10-08 11:57 3阅读 0赞

## 场景 ##

Android中点击按钮启动另一个Activity以及Activity之间传值：

[https://blog.csdn.net/BADAO\_LIUMANG\_QIZHI/article/details/103919470][https_blog.csdn.net_BADAO_LIUMANG_QIZHI_article_details_103919470]

在上面启动Activity和传值之后，怎样获取Acitvity的返回值。下面示例实现点击选择头像按钮，跳转到头像显示Activity，并将选择的图片的索引返回，在MainActivity中获取后设置头像。

### 效果 ###

![20200110113330703.gif][]

注：

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[https://blog.csdn.net/badao\_liumang\_qizhi][https_blog.csdn.net_badao_liumang_qizhi]  
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## 实现 ##

首先是主页面MainActivity的布局，添加一个选择头像按钮和一个ImageView用来显示头像。

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".MainActivity">
    
    <ImageView
        android:id="@+id/image"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
    
    <Button
        android:id="@+id/button"
        android:text="选择头像"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"/>
    
    </LinearLayout>

然后在MainActivity中的OnCreate方法中，使用startActivityForResult能启动另一个Activity并能获得返回结果。

要设置一个请求码，这里是200。

Button button = (Button)findViewById(R.id.button);
            button.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Intent intent = new Intent(MainActivity.this,HeadActivity.class);
                    startActivityForResult(intent,200);
                }
            });

然后跳转到第二个Activity用来选择头像。首先设置其布局文件，添加一个GridView用来显示要选择的头像照片。

activity\_head.xml

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        xmlns:app="http://schemas.android.com/apk/res-auto"
        xmlns:tools="http://schemas.android.com/tools"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:orientation="vertical"
        tools:context=".HeadActivity">
    
        <GridView
            android:id="@+id/gridView"
            android:numColumns="4"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"/>
    
    </LinearLayout>

然后来到其Activity，使用适配器为其设置照片源。

首先声明一个图片数组

private  int[] imageId = new int[]{
            R.drawable.img1,R.drawable.img2
        };

这里引用了drawable下的两张头像照片。

然后使用适配器为照片设置数据源

GridView gridView = (GridView) findViewById(R.id.gridView);
            BaseAdapter adapter = new BaseAdapter() {
                @Override
                public int getCount() {
                    return imageId.length;
                }
    
                @Override
                public Object getItem(int position) {
                    return null;
                }
    
                @Override
                public long getItemId(int position) {
                    return 0;
                }
    
                @Override
                public View getView(int position, View convertView, ViewGroup parent) {
                    ImageView imageView;
                    if(convertView ==null)
                    {
                        imageView = new ImageView(HeadActivity.this);
                        imageView.setAdjustViewBounds(true);
                        imageView.setMaxWidth(158);
                        imageView.setMaxHeight(150);
                        imageView.setPadding(5, 5, 5, 5);
    
                    }else
                    {
                        imageView = (ImageView) convertView;
                    }
                    imageView.setImageResource(imageId[position]);
                    return imageView;
                }
            };
    
            gridView.setAdapter(adapter);

然后在gridView的选项点击事件监听器中，获取选中照片的索引并通过Bundle对象的putInt和intent对象的putExtras将数据进行返回。然后调用 setResult(200,intent);将结果进行返回，这里的请求结果码也设置为200。

完整HeadActivity.java

package com.badao.selectimage;
    
    import androidx.appcompat.app.AppCompatActivity;
    
    import android.content.Intent;
    import android.os.Bundle;
    import android.view.View;
    import android.view.ViewGroup;
    import android.widget.AdapterView;
    import android.widget.BaseAdapter;
    import android.widget.GridView;
    import android.widget.ImageView;
    
    public class HeadActivity extends AppCompatActivity {
    
        private  int[] imageId = new int[]{
            R.drawable.img1,R.drawable.img2
        };
        @Override
        protected void onCreate(Bundle savedInstanceState) {        GridView gridView = (GridView) findViewById(R.id.gridView);
            BaseAdapter adapter = new BaseAdapter() {
                @Override
                public int getCount() {
                    return imageId.length;
                }
    
                @Override
                public Object getItem(int position) {
                    return null;
                }
    
                @Override
                public long getItemId(int position) {
                    return 0;
                }
    
                @Override
                public View getView(int position, View convertView, ViewGroup parent) {
                    ImageView imageView;
                    if(convertView ==null)
                    {
                        imageView = new ImageView(HeadActivity.this);
                        imageView.setAdjustViewBounds(true);
                        imageView.setMaxWidth(158);
                        imageView.setMaxHeight(150);
                        imageView.setPadding(5, 5, 5, 5);
    
                    }else
                    {
                        imageView = (ImageView) convertView;
                    }
                    imageView.setImageResource(imageId[position]);
                    return imageView;
                }
            };
    
            gridView.setAdapter(adapter);
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_head);
    
            gridView.setOnItemClickListener(new AdapterView.OnItemClickListener() {
                @Override
                public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
                    Intent intent = getIntent();
                    Bundle bundle = new Bundle();
                    bundle.putInt("imageId",imageId[position]);
                    intent.putExtras(bundle);
                    setResult(200,intent);
                    finish();
                }
            });
        }
    }

然后回到MainActivity怎样接受返回的结果。

ctrl + O重写方法 onActivityResult,如果请求码和返回结果码都是200,首先通过

Bundle bundle  = data.getExtras();

获取Bundle对象。

然后通过

int imageId = bundle.getInt("imageId");

获取返回的照片索引数据。

然后给ImageView设置照片源。

@Override
        protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
            super.onActivityResult(requestCode, resultCode, data);
            if(requestCode ==200 && resultCode == 200)
            {
                Bundle bundle  = data.getExtras();
                int imageId = bundle.getInt("imageId");
                ImageView imageView = (ImageView) findViewById(R.id.image);
                imageView.setImageResource(imageId);
    
            }
        }

MainActivity完整示例代码

package com.badao.selectimage;
    
    import androidx.annotation.Nullable;
    import androidx.appcompat.app.AppCompatActivity;
    
    import android.content.Intent;
    import android.os.Bundle;
    import android.view.View;
    import android.widget.Button;
    import android.widget.ImageView;
    
    public class MainActivity extends AppCompatActivity {
    
        @Override
        protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) {
            super.onActivityResult(requestCode, resultCode, data);
            if(requestCode ==200 && resultCode == 200)
            {
                Bundle bundle  = data.getExtras();
                int imageId = bundle.getInt("imageId");
                ImageView imageView = (ImageView) findViewById(R.id.image);
                imageView.setImageResource(imageId);
    
            }
        }
    
        @Override
        protected void onCreate(Bundle savedInstanceState) {
            super.onCreate(savedInstanceState);
            setContentView(R.layout.activity_main);
    
            Button button = (Button)findViewById(R.id.button);
            button.setOnClickListener(new View.OnClickListener() {
                @Override
                public void onClick(View v) {
                    Intent intent = new Intent(MainActivity.this,HeadActivity.class);
                    startActivityForResult(intent,200);
                }
            });
    
    
        }
    }

[https_blog.csdn.net_BADAO_LIUMANG_QIZHI_article_details_103919470]: https://blog.csdn.net/BADAO_LIUMANG_QIZHI/article/details/103919470
[20200110113330703.gif]: https://img-blog.csdnimg.cn/20200110113330703.gif
[https_blog.csdn.net_badao_liumang_qizhi]: https://blog.csdn.net/badao_liumang_qizhi