android学习笔记(23)listview进阶

r囧r小猫 2022-08-05 08:58 199阅读 0赞

目录结构:

![20150912151049595][]

MainActivity2

package com.example1.listviewpracticvce;
    /*
     * 本activity实现的功能:
     * 将数据库中的数据用listview显示出来
     */
    import com.example1.listviewdao.PersonDAO;
    
    import android.app.Activity;
    import android.content.Context;
    import android.database.Cursor;
    import android.os.Bundle;
    import android.view.View;
    import android.widget.AdapterView;
    import android.widget.ImageView;
    import android.widget.ListView;
    import android.widget.SimpleCursorAdapter;
    import android.widget.TextView;
    import android.widget.Toast;
    import android.widget.AdapterView.OnItemClickListener;
    import android.widget.SimpleCursorAdapter.ViewBinder;
    
    
    	public class MainActivity2 extends Activity {
    		ListView lvPerson;
    		@Override
    		protected void onCreate(Bundle savedInstanceState) {
    			super.onCreate(savedInstanceState);
    			setContentView(R.layout.person);
    			PersonDAO personDAO = new PersonDAO(this);
    			Cursor cursor = personDAO.getPersons();//cursor类似一个指针
    			lvPerson = (ListView) findViewById(R.id.lvPerson);
    			//SimpleCursorAdapter(context, layout,     c,     from,       to        )
    			//                       listview的布局       cursor  需要显示的列    在哪个控件中显示
    			//数组开头的列必须是"_id"
    			SimpleCursorAdapter adapter = new PersonAdapter(this, R.layout.person_item, cursor,
    					new String[]{ "_id", "pname", "pgender" },
    					new int[]{ R.id.tvPid, R.id.tvPname, R.id.ivPgender });
    //			SimpleCursorAdapter adapter = new SimpleCursorAdapter(this, R.layout.person_item, cursor, 
    //			new String[]{ "_id", "pname", "pgender" }, //要显示的列
    //			new int[]{ R.id.tvPid, R.id.tvPname, R.id.ivPgender });//显示每行所用控件
    //为了将性别显示为图片，这里复写了SimpleCursorAdapter这个类
    	        lvPerson.setAdapter(adapter);
    	    	lvPerson.setOnItemClickListener(new OnItemClickListener()
    			{
    
    				@Override
    				public void onItemClick(AdapterView<?> parent, View view, int position, long id)
    				{
    					Cursor cursor = (Cursor) parent.getItemAtPosition(position);
    					Toast.makeText(getApplicationContext(), cursor.getString(1), Toast.LENGTH_SHORT).show();
    				}
    			});
    		
    		}
    	}
    
    	//利用源代码定制
    	class PersonAdapter extends SimpleCursorAdapter
    	{
    		private Cursor mCursor;
    		protected int[] mFrom;
    		protected int[] mTo;
    
    		private ViewBinder mViewBinder;
    
    		public PersonAdapter(Context context, int layout, Cursor c, String[] from, int[] to)
    		{
    			super(context, layout, c, from, to);
    			mCursor = c;
    			mTo = to;
    			findColumns(from);
    		}
    
    		@Override
    		public void bindView(View view, Context context, Cursor cursor)
    		{
    			final ViewBinder binder = mViewBinder;
    			final int count = mTo.length;
    			final int[] from = mFrom;
    			final int[] to = mTo;
    
    			for (int i = 0; i < count; i++)
    			{
    				final View v = view.findViewById(to[i]);
    				if (v != null)
    				{
    					boolean bound = false;
    					if (binder != null)
    					{
    						bound = binder.setViewValue(v, cursor, from[i]);
    					}
    
    					if (!bound)
    					{
    						String text = cursor.getString(from[i]);
    						if (text == null)
    						{
    							text = "";
    						}
    
    						if (v instanceof TextView)
    						{
    							setViewText((TextView) v, text);
    						} else if (v instanceof ImageView)
    						{
    							if (text.equals("男"))
    							{
    								setViewImage((ImageView) v, String.valueOf(R.drawable.boy));
    							}
    							else
    							{
    								setViewImage((ImageView) v, String.valueOf(R.drawable.girl));
    							}
    							
    						} else
    						{
    							throw new IllegalStateException(v.getClass().getName() + " is not a " + " view that can be bounds by this SimpleCursorAdapter");
    						}
    					}
    				}
    			}
    		}
    
    		private void findColumns(String[] from)
    		{
    			if (mCursor != null)
    			{
    				int i;
    				int count = from.length;
    				if (mFrom == null || mFrom.length != count)
    				{
    					mFrom = new int[count];
    				}
    				for (i = 0; i < count; i++)
    				{
    					mFrom[i] = mCursor.getColumnIndexOrThrow(from[i]);
    				}
    			} else
    			{
    				mFrom = null;
    			}
    		}
    
    	}

DBOpenHelper

package com.example1.listviewdao;
    
    import android.content.Context;
    import android.database.sqlite.SQLiteDatabase;
    import android.database.sqlite.SQLiteOpenHelper;
    
    public class DBOpenHelper extends SQLiteOpenHelper
    {
    	private static final int VERSION = 1;
    	private static final String DBNAME = "data.db";
    	private static final String PERSON="t_person";
    	
    	public DBOpenHelper(Context context)
    	{
    		super(context, DBNAME, null, VERSION);
    	}
    
    	@Override
    	public void onCreate(SQLiteDatabase db)
    	{
    		db.execSQL("create table "+PERSON+" (_id varchar(4) primary key,pname varchar(20),pgender varchar(2))");
    		db.execSQL("insert into t_person (_id, pname, pgender) values ('1001','张三','男')");
    		db.execSQL("insert into t_person (_id, pname, pgender) values ('1002','李四','男')");
    		db.execSQL("insert into t_person (_id, pname, pgender) values ('1003','王五','女')");
    		db.execSQL("insert into t_person (_id, pname, pgender) values ('1004','赵钱','男')");
    		db.execSQL("insert into t_person (_id, pname, pgender) values ('1005','孙李','女')");
    		db.execSQL("insert into t_person (_id, pname, pgender) values ('1006','周吴','男')");
    		db.execSQL("insert into t_person (_id, pname, pgender) values ('1007','郑王','男')");
    		db.execSQL("insert into t_person (_id, pname, pgender) values ('1008','冯陈','男')");
    		db.execSQL("insert into t_person (_id, pname, pgender) values ('1009','褚卫','女')");
    		db.execSQL("insert into t_person (_id, pname, pgender) values ('1010','蒋沈','男')");
    		db.execSQL("insert into t_person (_id, pname, pgender) values ('1011','韩杨','男')");
    		db.execSQL("insert into t_person (_id, pname, pgender) values ('1012','朱秦','男')");
    		db.execSQL("insert into t_person (_id, pname, pgender) values ('1013','尤许','男')");
    	}
    
    	@Override
    	public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion)
    	{
    		
    	}
    }

Person

package com.example1.listviewdao;
    
    public class Person
    {
    	private String pid;
    	private String pname;
    	private String pgender;
    
    	public Person()
    	{
    		super();
    	}
    
    	public Person(String pid, String pname, String pgender)
    	{
    		super();
    		this.pid = pid;
    		this.pname = pname;
    		this.pgender = pgender;
    	}
    
    	public String getPid()
    	{
    		return pid;
    	}
    
    	public void setPid(String pid)
    	{
    		this.pid = pid;
    	}
    
    	public String getPname()
    	{
    		return pname;
    	}
    
    	public void setPname(String pname)
    	{
    		this.pname = pname;
    	}
    
    	public String getPgender()
    	{
    		return pgender;
    	}
    
    	public void setPgender(String pgender)
    	{
    		this.pgender = pgender;
    	}
    
    	@Override
    	public String toString()
    	{
    		return "pid=" + pid + ";pname=" + pname + ";pgender=" + pgender;
    	}
    }

PersonDAO

package com.example1.listviewdao;
    
    import android.content.Context;
    import android.database.Cursor;
    import android.database.sqlite.SQLiteDatabase;
    
    
    public class PersonDAO
    {
    	private DBOpenHelper helper;
    	private SQLiteDatabase db;
    
    	public PersonDAO(Context context)
    	{
    		helper = new DBOpenHelper(context);
    	}
    
    	public Cursor getPersons(int start, int count)
    	{
    		db = helper.getWritableDatabase();
    		Cursor cursor=db.query("t_person", new String[]{"_id","pname","pgender"}, null, null, null, null, "_id desc",start+","+count);
    		return cursor;
    	}
    	
    	public Cursor getPersons()
    	{
    		db = helper.getWritableDatabase();
    		Cursor cursor=db.query("t_person", new String[]{"_id,pname,pgender"}, null, null, null, null, null);
    		return cursor;
    	}
    	
    	public long getCount()
    	{
    		db = helper.getWritableDatabase();
    		Cursor cursor = db.rawQuery("select count(_id) from t_person", null);
    		if (cursor.moveToNext())
    		{
    			return cursor.getLong(0);
    		}
    		return 0;
    	}
    }

person\_item.xml

person.xml

<?xml version="1.0" encoding="utf-8"?>
    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
        android:orientation="vertical"
        android:layout_width="fill_parent"
        android:layout_height="fill_parent"
        >
    	<LinearLayout
    	    android:orientation="horizontal"
    	    android:layout_width="fill_parent"
    	    android:layout_height="wrap_content"
    	    >
    		<TextView  
    		    android:layout_width="70dp" 
    		    android:layout_height="wrap_content" 
    		    android:gravity="center"
    		    android:text="编号"
    		    android:textSize="20sp"
    		    android:textStyle="bold"
    		    />
    		<TextView
    			android:layout_width="190dp"
    			android:layout_height="wrap_content"
    			android:gravity="center"
    			android:text="姓名"
    			android:textSize="20sp"
    		    android:textStyle="bold"
    			/>
    		<TextView
    			android:layout_width="wrap_content"
    			android:layout_height="wrap_content"
    			android:text="性别"
    			android:textSize="20sp"
    		    android:textStyle="bold"
    			/>
    	</LinearLayout>
    	<ListView
    		android:id="@+id/lvPerson"
    		android:layout_width="match_parent"
    		android:layout_height="wrap_content"
    		android:background="@drawable/bg"
    		android:scrollingCache="false"
    		android:divider="@drawable/line"
    		/>
    </LinearLayout>

![20150912151105809][]

[20150912151049595]: /images/20220731/42e9b9124956478dae930dfa107e3e1e.png
[20150912151105809]: /images/20220731/917adebcc30049a9aa8f15758fde81ce.png