2018-2019-2 20175215 实验二《面向对象程序设计》实验报告

一、实验内容及步骤

1.单元测试

（1）安装JUnit
点击File，然后点击setting

搜索框中输入JUnit后选择JunitGenerator V2.0

安装完成之后重启IDEA就可以了，安装成功之后的效果如图所示：
（2）TDD
TDD的编码节奏是：
- 增加测试代码，JUnit出现红条
- 修改产品代码
- JUnit出现绿条，任务完成

2.任务一：在一个MyUtil类中解决一个百分制成绩转成“优、良、中、及格、不及格”五级制成绩的功能。

产品代码：

public class MyUtil{
    public static String percentage2fivegrade(int grade){
        //如果成绩小于0，转成“错误”
        if ((grade < 0))
            return "错误";
            //如果成绩小于60，转成“不及格”
        else if (grade < 60)
            return "不及格";
            //如果成绩在60与70之间，转成“及格”
        else if (grade < 70)
            return "及格";
            //如果成绩在70与80之间，转成“中等”
        else if (grade < 80)
            return "中等";
            //如果成绩在80与90之间，转成“良好”
        else if (grade < 90)
            return "良好";
            //如果成绩在90与100之间，转成“优秀”
        else if (grade <=100)
            return "优秀";
            //如果成绩大于100，转成“错误”
        else
            return "错误";
    }
}

测试代码：

import org.junit.Test;
import junit.framework.TestCase;
public class MyUtilTest extends TestCase {
    @Test
    public void testNormal() {
        assertEquals("不及格", MyUtil.percentage2fivegrade(55));
        assertEquals("及格", MyUtil.percentage2fivegrade(65));
        assertEquals("中等", MyUtil.percentage2fivegrade(75));
        assertEquals("良好", MyUtil.percentage2fivegrade(85));
        assertEquals("优秀", MyUtil.percentage2fivegrade(95));
    }
    @Test
    public void testExceptions(){
        assertEquals("错误",MyUtil.percentage2fivegrade(-55));
        assertEquals("错误",MyUtil.percentage2fivegrade(105));
    }
    @Test
    public void testBoundary(){
        assertEquals("不及格",MyUtil.percentage2fivegrade(0));
        assertEquals("及格",MyUtil.percentage2fivegrade(60));
        assertEquals("中等",MyUtil.percentage2fivegrade(70));
        assertEquals("良好",MyUtil.percentage2fivegrade(80));
        assertEquals("优秀",MyUtil.percentage2fivegrade(90));
        assertEquals("优秀",MyUtil.percentage2fivegrade(100));
    }
}

系统反馈结果，如果测试失败，IDEA会指出具体哪个测试用例出现错误，修改代码直至所有测试均通过
测试成功截图

3.任务二：以TDD的方式研究学习StringBuffer

老师给出的StringBuffer的例子：

public class StringBufferDemo{        
   public static void main(String [] args){    
      StringBuffer buffer = new StringBuffer();    
       buffer.append('S');     
       buffer.append("tringBuffer");     
       System.out.println(buffer.charAt(1));     
       System.out.println(buffer.capacity());     
       System.out.println(buffer.indexOf("tring"));    
       System.out.println("buffer = " + buffer.toString());    
  }    
}

对代码进行改写，使得其可以进行JUnit测试

public class StringBufferDemo{
    StringBuffer buffer = new StringBuffer();
    public StringBufferDemo(StringBuffer buffer){
        this.buffer = buffer;
    }
    public Character charAt(int i){
        return buffer.charAt(i);
    }
    public int capacity(){
        return buffer.capacity();
    }
    public int length(){
        return buffer.length();
    }
    public int indexOf(String buf) {
        return buffer.indexOf(buf);
    }
}

各方法的作用如下：
- charAt（int i）：得到字符串中第i个位置的字符，考虑到数组下标从0开始，字符串的位置也从0开始记。
- capacity（）：返回当前容量。容量指可用于最新插入的字符的存储量，超过这一容量就需要再次进行分配。
- length()：得到字符串长度
- indexOf（String buf）：得到buf字符串第一次出现的位置，该位置为buf中第一个字符的位置
测试代码：

import junit.framework.TestCase;
import org.junit.Test;

public class StringBufferDemoTest extends TestCase {
    StringBuffer a1 = new StringBuffer("StringBuffer");
    StringBuffer a2 = new StringBuffer("StringBufferStringBuffer");
    StringBuffer a3 = new StringBuffer("StringBuffer used by 20175215");
    @Test
    public void testCharAt() throws Exception{//验证返回是否是整个字符串中的第x个字符
        assertEquals('S',a1.charAt(0));
        assertEquals('t',a2.charAt(13));
        assertEquals('b',a3.charAt(18));
    }
    @Test
    public void testcapacity() throws Exception{//验证容量
        assertEquals(28,a1.capacity());
        assertEquals(40,a2.capacity());
        assertEquals(45,a3.capacity());
    }
    @Test
    public void testlength() throws Exception{//验证字符串的长度
        assertEquals(12,a1.length());
        assertEquals(24,a2.length());
        assertEquals(29,a3.length());
    }
    @Test
    public void testindexOf(){//验证所在位置
        assertEquals(6,a1.indexOf("Buff"));
        assertEquals(1,a2.indexOf("tring"));
        assertEquals(25,a3.indexOf("5215"));
    }
}

测试成功截图

4.任务三：对设计模式示例进行扩充，体会OCP原则和DIP原则的应用，初步理解设计模式

我的学号%6进行取余运算的结果（15%6）为3，让系统支持Long类，并在MyDoc类中添加测试代码表明添加正确。

引用20175308杨元同学关于S.O.L.I.D原则的笔记

依据OCP原则和DIP原则，我们在扩充示例使其支持Long类时不应该直接添加或修改已有类中的方法（OCP原则要求软件实体对修改封闭），而是采用一种抽象工厂的方法来进行对于程序的扩充。具体代码如下：

abstract class Data {
    abstract public void DisplayValue();
}
class Integer extends  Data {
    int value;
    Integer() {
        value=100;
    }
    public void DisplayValue(){
        System.out.println (value);
    }
}
class Long extends Data{
    long value;
    Long(){
        value=1234567890;
    }
    public void DisplayValue(){
        System.out.println(value);
    }
}
abstract class Factory {
    abstract public Data CreateDataObject();
}
class IntFactory extends Factory {
    public Data CreateDataObject(){
        return new Integer();
    }
}
class LongFactory extends Factory{
    public Data CreateDataObject(){
        return new Long();
    }
}
class Document {
    Data pd;
    Document(Factory pf){
        pd = pf.CreateDataObject();
    }
    public void DisplayData(){
        pd.DisplayValue();
    }
}
//Test class
public class MyDoc {
    static Document d;
    static Document e;
    public static void main(String[] args) {
        d = new Document(new IntFactory());
        d.DisplayData();
        e=new Document(new LongFactory());                                                   //20175215
        e.DisplayData();

    }
}

运行成功截图:

5.任务四：以TDD的方式开发一个复数类Complex。

参考Java DecimalFormat 用法（数字格式化），加入import java.text.DecimalFormat;进行编程。

测试代码：

import junit.framework.TestCase;
import org.junit.Test;

public class ComplexTest extends TestCase {
    Complex a1 =new Complex(3.0,4.0);
    Complex a2 =new Complex( 2.0,-4.0);
    Complex a3 =new Complex(0.0,0.0);
    Complex a4 =new Complex(-3.0,0.0);
    Complex a5 =new Complex(-6.0,-0.8);
    @Test
    public void testgetRealPart()throws Exception{
        assertEquals(3.0,a1.getReal());
        assertEquals(2.0,a2.getReal());
        assertEquals(0.0,a3.getReal());
        assertEquals(-3.0,a4.getReal());
        assertEquals(-6.0,a5.getReal());
    }
    @Test
    public void testgetImagePart()throws Exception{
        assertEquals(4.0,a1.getImaginary());
        assertEquals(-4.0,a2.getImaginary());
        assertEquals(0.0,a3.getImaginary());
        assertEquals(0.0,a4.getImaginary());
        assertEquals(-0.8,a5.getImaginary());

    }
    @Test
    public void testtoString()throws Exception{
        assertEquals("3.0+4.0i",a1.toString());
        assertEquals("2.0-4.0i",a2.toString());
        assertEquals("0",a3.toString());
        assertEquals("-3.0",a4.toString());
        assertEquals("-6.0-0.8i",a5.toString());
    }
    @Test
    public void testComplexAdd()throws Exception{
        assertEquals("5.0",a1.ComplexAdd(a2).toString());
        assertEquals("2.0-4.0i",a2.ComplexAdd(a3).toString());
        assertEquals("-3.0",a3.ComplexAdd(a4).toString());
    }
    @Test
    public void testComplexSub()throws Exception{
        assertEquals("1.0+8.0i",a1.ComplexSub(a2).toString());
        assertEquals("-2.0+4.0i",a3.ComplexSub(a2).toString());
        assertEquals("3.0",a3.ComplexSub(a4).toString());
    }
    @Test
    public void testComplexMulti()throws Exception{
        assertEquals("22.0-4.0i",a1.ComplexMulti(a2).toString());
        assertEquals("0",a2.ComplexMulti(a3).toString());
        assertEquals("18.0+2.4i",a4.ComplexMulti(a5).toString());
    }
    @Test
    public void testComplexDiv()throws Exception{
        assertEquals("-0.2-1.2i",a1.ComplexDiv(a2).toString());
        assertEquals("0",a3.ComplexDiv(a2).toString());
    }
    @Test
    public void testequals()throws Exception{
        assertEquals(true,a1.equals(a1));
        assertEquals(false,a1.equals(a2));

    }
}

产品代码

import java.text.DecimalFormat;//引入DecimalFormat包取一位整数和一位小数

public class Complex {
    double Real=0;
    double Imaginary=0;
    public Complex(){}
    public Complex(double Real,double Imaginary){
        this.Real=Real;
        this.Imaginary=Imaginary;

    }
    public double getReal(){
        return Real;
    }
    public double getImaginary(){
        return Imaginary;
    }
    public String toString(){
        String s = "";
        double r=Real;
        double i=Imaginary;
        if(r==0&&i==0){
            s="0";
        }
        else if(r==0&&i!=0){
            s=i+"i";
        }
        else if(r!=0&&i<0){
            s=r+""+i+"i";
        }
        else if(r!=0&&i==0){
            s=r+"";
        }
        else
        {
            s=r+"+"+i+"i";
        }
        return s;
    }
    public boolean equals(Object obj){//重写equals方法，使其不用来对比字符序列
        if(this==obj){
            return true;
        }
        else
            return false;
    }
    DecimalFormat df = new DecimalFormat( "0.0");
    public Complex ComplexAdd(Complex a){
        return new Complex(Real+a.getReal(),Imaginary+a.getImaginary());
    }
    public Complex ComplexSub(Complex a){
        return new Complex(Real-a.getReal(),Imaginary-a.getImaginary());
    }
    public Complex ComplexMulti(Complex a){
        double r=Real*a.getReal()-Imaginary*a.getImaginary();
        double i =Imaginary*a.getReal()+Real*a.getImaginary();
        return new Complex(Double.valueOf(df.format(r)),Double.valueOf(df.format(i)));
    }
    public Complex ComplexDiv(Complex a){
        double r=(Real * a.Imaginary + Imaginary * a.Real) / (a.Imaginary * a.Imaginary + a.Real * a.Real);
        double i=(Imaginary * a.Imaginary + Real * a.Real) / (a.Real * a.Real + a.Real * a.Real);
        return new Complex(Double.valueOf(df.format(r)),Double.valueOf(df.format(i)));
    }
}