关于持续按键有关问题

关于持续按键问题
请问我这段代码哪里有问题啊，我这个按下一个键就一直动了，放开了也在动。我想做到的是按下一个键就朝一个方向一直动，放开了就不动
public class Player
{
int player_x = 0;
int player_y = 0;

int player_w = 16; //每格人物图象的宽
int player_h = 32; //每格人物图象的高

int player_dir = 4; //0为下，1为左，2为右，3为上，4为不动

int playerFrameIndex;//当前的贞

int player_speed = 2;

int old_dir;

boolean isUp = false;
boolean isDown = false;
boolean isLift = false;
boolean isRight = false;

public Player(int x,int y,int dir) 
{
player_x = x;
player_y = y;
player_dir = dir;
}

public void draw(Graphics g,Image player,Image player4)
{
g.setClip(player_x, player_y, player_w, player_h);
g.drawImage(player, player_x - playerFrameIndex * player_w, player_y - player_dir * player_h, 20);
move();
}

void move()
{
switch(player_dir)
{
case 0:
player_y += player_speed;
break;

case 1:
player_x -= player_speed;
break;

case 2:
player_x += player_speed;
break;

case 3:
player_y -= player_speed;
break;
}
updata();
}

public void keyPressed(int keyCode) 
{
switch(keyCode)
{
case KeyMap.KEY_2:
isUp = true;
break;

case KeyMap.KEY_UP:
isUp = true;
break;

case KeyMap.KEY_4:
isLift = true;
break;

case KeyMap.KEY_LEFT:
isLift = true;
break;

case KeyMap.KEY_6:
isRight = true;
break;

case KeyMap.KEY_RIGHT:
isRight = true;
break;

case KeyMap.KEY_8:
isDown= true;
break;

case KeyMap.KEY_DOWN:
isDown = true;
break;
}
setDirection();
}

public void keyReleased(int keyCode) 
{
switch(keyCode)
{
case KeyMap.KEY_2:
isUp = false;
break;

case KeyMap.KEY_UP:
isUp = false;
break;

case KeyMap.KEY_4:
isLift = false;
break;

case KeyMap.KEY_LEFT:
isLift = false;
break;

case KeyMap.KEY_6:
isRight = false;
break;

case KeyMap.KEY_RIGHT:
isRight = false;
break;

case KeyMap.KEY_8:
isDown= false;
break;

case KeyMap.KEY_DOWN:
isDown = false;
break;
}
setDirection();
}

void setDirection()
{
if(!isLift && !isUp && !isRight && isDown) //如果只有isDown被激活，即isDown值为true
{
player_dir = 0; //则把人物的方向设置为0，0代表下
}
else if(isLift && !isUp && !isRight && !isDown) //如果只有isLift被激活，即isLift值为true
{
player_dir = 1; //则把人物的方向设置为1，1代表左
}
else if(!isLift && !isUp && isRight && !isDown) //如果只有isRight被激活，即isRight值为true
{
player_dir = 2; //则把人物的方向设置为2，2代表右
}
else if(!isLift && isUp && !isRight && !isDown) //如果只有isUp被激活，即isUp值为true
{
player_dir = 3; //则把人物的方向设置为3，3代表上
}
}

void updata()
{
playerFrameIndex++;
playerFrameIndex %= 3;
}
}

------解决方案--------------------------------------------------------
你写一个按键检测方法，把它放到run()里面，在这个方法外用boolean的变量is_key_down判断按键状态。keyPressed()里面写is_key_down=true；表示按键按下；在keyReleased()里写is_key_down=false;表示按键抬起。

代码：

Java code

private int key1;//按键键值private boolean is_key_down;//按键状态/** *系统方法，按下按键 * */public void keyPressed(int key){  is_key_down=true;  key1=key;//传参}/** *系统方法，抬起按键 * */public void keyReleased(int key){  is_key_down=false;}/** *你的代码中写在keyPressed里的switch语句 * */private void keySet(int key){  switch(key){  }}public void run(){  if(is_key_down)    keySet(key1);//自定义方法}