异常处理和画板的保存

来源：互联网发布：北航软件学院分数线编辑：程序博客网时间：2024/05/17 07:25

前几天超哥给我们讲了异常处理，左哥给我们讲了数据读取和数据保存。我做了用户名检测和画图板的保存。

其中异常的处理我做了用户名的检测，就是给用户抛出异常，让用户自己处理。下面是核心检测代码:

public void check(String name) throws Exception{char[] s = name.toCharArray() ;if(s[0] >= '0'&&s[0] <='9'){throw new Exception("用户名不能以数字开头");}if(s.length >= 10){throw new Exception("用户名不能超过十位");}for(int i = 1;i<s.length; i++){if(s[i]>='0'&&s[i]<='9'){break;}if(i == s.length -1){throw new Exception("用户名必须含有数字");}}JOptionPane.showMessageDialog(this, "用户名可用");}

jb.addActionListener(new ActionListener(){public void actionPerformed(ActionEvent arg0) {try {check(text1.getText());} catch (Exception e) {JOptionPane.showMessageDialog(UserTest.this, e.getMessage());}}});

画图板的保存核心代码：

try {FileOutputStream fos = new FileOutputStream(file);DataOutputStream dos = new DataOutputStream(fos);for(int i=0;i<Draw.list.size();i++){Shape shape = Draw.list.get(i);if(shape instanceof Line){dos.writeByte(1);}if(shape instanceof Oval){dos.writeByte(2);}if(shape instanceof Rect){dos.writeByte(3);}dos.writeInt(shape.x1);dos.writeInt(shape.y1);dos.writeInt(shape.x2);dos.writeInt(shape.y2);String s = Color2String(shape.color);dos.writeUTF(s);}

其中打开保存文件是:

try {FileInputStream fis = new FileInputStream(file);DataInputStream dis = new DataInputStream(fis);while(dis.available()>0){int type = dis.readByte();if(type==1){int x1 = dis.readInt();int y1 = dis.readInt();int x2 = dis.readInt();int y2 = dis.readInt();String s = dis.readUTF();Color color = String2Color(s);Shape line = new Line(x1, x2, y1, y2, color);Draw.list.add(line);}if(type==2){int x1 = dis.readInt();int y1 = dis.readInt();int x2 = dis.readInt();int y2 = dis.readInt();String s = dis.readUTF();Color color = String2Color(s);Shape oval = new Oval(x1, x2, y1, y2, color);Draw.list.add(oval);}if(type==3){int x1 = dis.readInt();int y1 = dis.readInt();int x2 = dis.readInt();int y2 = dis.readInt();String s = dis.readUTF();Color color = String2Color(s);Shape rect = new Rect(x1, x2, y1, y2, color);Draw.list.add(rect);}}

其中我遇到了如何保存颜色属性的难题，我是想通过保存字符串来保存的，但是代码不会写，于是就在网上摘录下来了。

就是一下2个方法:

public static Color String2Color(String str){int i = Integer.parseInt(str.substring(1),16);return new Color(i);} public static String Color2String(Color color) {  String R = Integer.toHexString(color.getRed());  R = R.length()<2?('0'+R):R;  String B = Integer.toHexString(color.getBlue());  B = B.length()<2?('0'+B):B;  String G = Integer.toHexString(color.getGreen());  G = G.length()<2?('0'+G):G;  return '#'+R+B+G; }

还有就是要停课了，因为接近期末了，华信给我1个月的复习时间，让我们有充足的时间去复习考试。到1月18号就开始华信的寒假集训了，我很期待呢

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