Android中ListView使用总结

在android开发中，ListView是比较常用的组件，以列表形式展示具体内容，并根据数据长度自适应显示

Adapter是连接后端数据和前端显示的适配器接口，是数据和UI（View）之间一个重要的纽带。

简单的ListView使用这里不赘述，这里说下ListView自定义数据和自定义adapter时的较复杂点的使用，

作抛砖引玉

先上最终效果图，左面是一个图片，右面有一些文字描述

主视图布局配置是这样的，只呈现一个ListView

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
    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:orientation="vertical"
    android:padding="@dimen/activity_horizontal_margin"
    tools:context="com.xuexi.zhaoyun.testadapter.CustomListView">

    <ListView
        android:id="@+id/customListView"
        android:layout_width="match_parent"
        android:layout_height="match_parent">

    </ListView>
</LinearLayout>

先自定义一个数据类

package com.xuexi.zhaoyun.testadapter;

//自定义列表项数据类
public class CustomListCellData {

    public String name = "";
    public String dec = "";
    public int iconId = 0;

    public CustomListCellData(String userName, String dec, int iconId) {
        this.name = userName;
        this.dec = dec;
        this.iconId = iconId;
    }

    public String getUserName() {
        return name;
    }

    public void setUserName(String userName) {
        this.name = userName;
    }

    public String getDec() {
        return dec;
    }

    public void setDec(String dec) {
        this.dec = dec;
    }

    public int getIconId() {
        return iconId;
    }

    public void setIconId(int iconId) {
        this.iconId = iconId;
    }

}

定义一个列表项的布局

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:orientation="horizontal">

    <ImageView
        android:id="@+id/cion"
        android:layout_width="100dp"
        android:layout_height="100dp" />

    <LinearLayout
        android:layout_width="wrap_content"
        android:layout_height="100dp"
        android:layout_weight="1"
        android:gravity="center_vertical"
        android:orientation="vertical">

        <TextView
            android:id="@+id/name"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Large Text"
            android:textAppearance="?android:attr/textAppearanceLarge" />

        <TextView
            android:id="@+id/dec"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Small Text"
            android:textAppearance="?android:attr/textAppearanceSmall" />
    </LinearLayout>
</LinearLayout>

接下来就可以自定义adapter了，比较难理解的是getView

package com.xuexi.zhaoyun.testadapter;

import android.content.Context;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
import android.widget.BaseAdapter;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.TextView;


public class CustomListViewAdapter extends BaseAdapter {

    private Context context;

    public CustomListViewAdapter(Context context) {
        this.context = context;
    }

    public Context getContext() {
        return context;
    }

    //定义数据源
    private CustomListCellData[] data = new CustomListCellData[]{
            new CustomListCellData("小李", "是个歌手", R.drawable.ai_logo),
            new CustomListCellData("小王", "是个学生", R.drawable.bat_logo),
            new CustomListCellData("小魏", "是个屌丝", R.drawable.html_logo),
            new CustomListCellData("小薛", "是个闷骚男", R.drawable.z_logo),
    };

    @Override
    public int getCount() {
        return data.length;
    }

    @Override
    public CustomListCellData getItem(int i) {
        return data[i];
    }

    @Override
    public long getItemId(int i) {
        return i;
    }

    //用于构建最终展示在ListView里的每一项
    @Override
    public View getView(int i, View view, ViewGroup viewGroup) {

        /**
         * 这里需要解析自定义的用于展示每一个列表项的布局，并给相关组件赋值
         * 这里使用的是一个Android提供的优化机制，减少getView的触发次数，减少内存消耗
         * View是由getView创建但不在使用被系统回收的组件
         */
        LinearLayout ll = null;
        if (view!=null){
            ll = (LinearLayout) view;
        }else {
            ll = (LinearLayout) LayoutInflater.from(getContext()).inflate(R.layout.custom_listcell, null);
        }

        //先取到这一列表项的数据
        CustomListCellData data = getItem(i);

        ImageView icon = (ImageView) ll.findViewById(R.id.cion);
        TextView name = (TextView) ll.findViewById(R.id.name);
        TextView dec = (TextView) ll.findViewById(R.id.dec);

        //给布局里的相关组件设置数据
        icon.setImageResource(data.iconId);
        name.setText(data.name);
        dec.setText(data.dec);

        return ll;
    }
}

主视图代码非常简单

package com.xuexi.zhaoyun.testadapter;

import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.ListView;

public class CustomListView extends AppCompatActivity {

    private ListView customListView;

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

        customListView = (ListView) findViewById(R.id.customListView);
        customListView.setAdapter(new CustomListViewAdapter(this));
    }
}

以上。