filtertest.java

java手机程序开发随书光盘源代码

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import javax.microedition.rms.*;
import java.io.*;

public class FilterTest extends MIDlet implements CommandListener{

	Display display;
	RecordStore scoreStore;
	Command exitCmd;
	Command searchCmd;
	Alert results;
	List condition;
	String[] names = {"小明", "阿花", "大牛"};
	int[] math = {72, 98, 80};
	int[] chinese = {15, 80, 100};
	int[] english = {40, 62, 55};
	int numOfRecords;

	public FilterTest(){
		display = Display.getDisplay(this);
		condition = new List("选择筛选科目",Choice.MULTIPLE);
		condition.append("数学", null);
		condition.append("语文", null);
		condition.append("英语", null);
		results = new Alert("筛选结果");
		results.setTimeout(Alert.FOREVER);
		exitCmd = new Command("退出",Command.EXIT,1);
		searchCmd = new Command("筛选",Command.SCREEN,1);
		condition.addCommand(exitCmd);
		condition.addCommand(searchCmd);
		condition.setCommandListener(this);
		try{
			scoreStore = RecordStore.openRecordStore("score", true);
			numOfRecords = scoreStore.getNumRecords();
		}
		catch(Exception ex){}
		if(numOfRecords == 0){
			for(int i=0;i<names.length;i++){
				Score score = new Score(names[i], math[i], chinese[i], english[i]);
				score.writeToRecord(scoreStore);
			}
		}
	}

	public void startApp(){
		display.setCurrent(condition);
	}

	public void search(int choice){
		String searchingResult = "";
		boolean[] selected = new boolean[3];
		int num = condition.getSelectedFlags(selected);
		if(num == 0){
			searchingResult = "未设定筛选条件";
			results.setString(searchingResult);
			return;
		}
		for(int i=0;i<selected.length;i++){
        	if(selected[i]){
        		searchingResult += condition.getString(i)+" ";
        	}
        }
        searchingResult += "及格的是\n";
        MyFilter mf = new MyFilter();
        mf.setFilteredItem(choice);
		try{
			RecordEnumeration renum = scoreStore.enumerateRecords(mf, null, false);
			while(renum.hasNextElement()){
				Score score = new Score();
				score.readFromRecord(scoreStore, renum.nextRecordId());
				searchingResult += ""+score.name+"\n";
			}
			renum.destroy();
		}
		catch(Exception ex){}
		results.setString(searchingResult);
	}

	public void pauseApp(){
	}

	public void destroyApp(boolean unconditional){
		try{
			scoreStore.closeRecordStore();
		}
		catch(Exception ex){}
	}

	public void commandAction(Command c, Displayable d){
		if(c == exitCmd){
			destroyApp(true);
			notifyDestroyed();
		}
		else if(c == searchCmd){
			int choice = 1;
			boolean[] selected = new boolean[3];
        	condition.getSelectedFlags(selected);
        	for(int i=0;i<selected.length;i++){
        		if(selected[i]){
        			choice += 2*i;
        		}
        	}
			search(choice);
			display.setCurrent(results);
		}
	}
}

class Score{

	String name;
	int math;
	int chinese;
	int english;

	public Score(){
	}

	public Score(String name, int math, int chinese, int english){
		this.name = name;
		this.math = math;
		this.chinese = chinese;
		this.english = english;
	}

	public void writeToRecord(RecordStore rs){
		byte[] data = null;
		try{
			ByteArrayOutputStream baos = new ByteArrayOutputStream();
			DataOutputStream dos = new DataOutputStream(baos);
			dos.writeUTF(name);
			dos.writeInt(math);
			dos.writeInt(chinese);
			dos.writeInt(english);
			data = baos.toByteArray();
			rs.addRecord(data, 0, data.length);
			baos.close();
			dos.close();
		}
		catch(Exception ex){
		}
	}

	public void readFromRecord(RecordStore rs, int RecordID){
		try{
			byte[] data = rs.getRecord(RecordID);
			ByteArrayInputStream bais = new ByteArrayInputStream(data);
			DataInputStream dis = new DataInputStream(bais);
			name = new String(dis.readUTF());
			math = dis.readInt();
			chinese = dis.readInt();
			english = dis.readInt();
			bais.close();
			dis.close();
		}
		catch(Exception ex){}
	}
}

class MyFilter implements RecordFilter{

	static final int MATH = 1;
	static final int CHINESE = 2;
	static final int ENGLISH = 4;
	int filterItem;

	public void setFilteredItem(int item){
		filterItem = item;
	}

	public boolean matches(byte[] candidate){
		int math = 0, chinese = 0, english = 0;
		boolean matched = false;
		try{
			ByteArrayInputStream bais = new ByteArrayInputStream(candidate);
			DataInputStream dis = new DataInputStream(bais);
			String name = dis.readUTF();
			math = dis.readInt();
			chinese = dis.readInt();
			english = dis.readInt();
			dis.readInt();
			bais.close();
			dis.close();
		}
		catch(Exception ex){}
		if((filterItem & 0x01) == MATH)
			matched = (math>=60)?true:false;
		if((filterItem & 0x02) == CHINESE)
			matched = (chinese>=60)?true:false;
		if((filterItem & 0x04) == ENGLISH)
			matched = (english>=60)?true:false;
		return matched;
	}
}