由于公司项目需要对两个文件进行比较.(其实是数据库文本字段)
并且显示异同.
这里不是进行一个简单的比较.有一个文件就是
text1 1234
text2 012324
这两个文件并不是一个字段都不同.所以用一个一个 对比的办法是不可能的.因为text2 只是在 text1的基础上
在首字母上面增加了一个0 其他的没有改变...由于项目紧..没有自己实现..(自己实现也没有什么太好的思路)
这里就不讨论原理了..
http://www.incava.org/projects/java/java-diff/
这个是开源的解决方案..在网络上面找到的.分享下.
实现很简单一共有两个类..两jar包都没有..直接把源文件放到工程下面进行测试..
demo也是很简单的.
Object[] a = new Object[] {
"a",
"b",
"c",
"d",
"e"
};
Object[] b = new Object[] {
"a",
"x",
"y",
"b",
"c",
"j",
"e",
};
Difference[] expected = new Difference[] {
new Difference(1, -1, 1, 2),
new Difference(3, 3, 5, 5),
};
Diff diff = new Diff(a, b);
List diffOut = diff.diff();
要求输入的是一个Object[] 或是一个Collection的接口...
这个就不说你是怎么将你的文件转换成数组了.
String strs = "123456";
char[] strChars = strs.toCharArray();
Object[] objs = new Object[strChars.length];
for( int i = 0; i < strChars.length; i ++){
objs[i] = strChars[i];
}
下面看这个代码:
public static void main(String[] args) {
Object[] a = new Object[] { "a", "b", "c", "d", "e" };
Object[] b = new Object[] { "a", "x", "y", "b", "c", "j", "e", };
Diff diff = new Diff(a, b);
List diffOut = diff.diff();
for (int i = 0; i < diffOut.size(); i++) {
Difference diffce = (Difference) diffOut.get(i);
System.out.println(diffce);
}
}
在main函数里面运行:
显示结果:
del: [1,-1] add: [1,2]
del: [3,3] add: [5,5]
其中difference是显示不同的类下面有4个属性:
/**
* The point at which the deletion starts.
*/
private int delStart = NONE;
/**
* The point at which the deletion ends.
*/
private int delEnd = NONE;
/**
* The point at which the addition starts.
*/
private int addStart = NONE;
/**
* The point at which the addition ends.
*/
private int addEnd = NONE;
当delEnd 或 addEnd 为 -1 的时候表示不进行操作.
//abcde //01234 //a<add>xy</add>cde //0 12 345 //a<add>xy</add>c<del>d</del>e //0 12 3 4 //a<add>xy</add>bc<del>d</del><add>j</add>e //0 12 34 5 6
图示:<add>表示增加<del>表示删除.
del: [1,-1] 没有删除 add: [1,2]向a [1]中添加[1][2]
del: [3,3] 删除a中[3] add: [5,5] 向a中添加[5]
[start,end]表示操作的数组下标从0开始.起始结束.
注:进行了del操作.数组长度减少.添加数组长度增加.
其中你自己调用.delStart,delEnd , addStart,addEnd就可以对数组进行标示了....
如果代码中的<add>换成其他的<b>标签就可以在html中.显示文件的不同了.
public static void main(String[] args) {
Object[] a = new Object[] { "a", "b", "c", "d", "e" };
Object[] b = new Object[] { "a", "x", "y", "b", "c", "j", "e" };
Diff diff = new Diff(a, b);
List diffOut = diff.diff();
for (int i = 0; i < diffOut.size(); i++) {
Difference diffce = (Difference) diffOut.get(i);
System.out.println(diffce);
}
// abcde
// 01234
// a<add>xy</add>cde
// 0 12 345
// a<add>xy</add>c<del>d</del>e
// 0 12 3 4
// a<add>xy</add>bc<del>d</del><add>j</add>e
// 0 12 34 5 6
ArrayList list = new ArrayList();
for (int i = 0; i < a.length; i++) {
list.add(a[i]);
}
for (int i = 0; i < diffOut.size(); i++) {
Difference tempDiff = (Difference) diffOut.get(i);
int delStart = tempDiff.getDeletedStart();
int delEnd = tempDiff.getDeletedEnd();
int addStart = tempDiff.getAddedStart();
int addEnd = tempDiff.getAddedEnd();
if (delEnd != -1) {
// delEnd == -1 就是不进行刪除...
// 删除开始.
for (int j = delStart; j <= delEnd; j++) {
// 删除多个.
list.remove(j);
if (delStart != 0) {
String temp = list.get(delStart - 1).toString();
list.remove(delStart - 1);
list
.add(delStart - 1, temp + "<del>" + b[j]
+ "</del>");
} else {
String temp = list.get(0).toString();
list.remove(0);
list.add(0, temp + "<del>" + b[j] + "</del>");
}
pirntList(list);
}
}
if (addEnd != -1) {
// addEnd == -1 就是不进行添加...
// 下面添加的情况..
for (int j = addStart; j <= addEnd; j++) {
// 添加多个.
if (addStart > list.size()) {
list.add("<add>" + b[j] + "</add>");
} else {
list.add(addStart, "<add>" + b[j] + "</add>");
}
pirntList(list);
}
}
}
pirntList(list);
// return buffer.toString();
}
public static void pirntList(List list) {
StringBuffer buffer = new StringBuffer();
for (int i = 0; i < list.size(); i++) {
buffer.append(""+list.get(i));
}
System.out.println(buffer.toString());
}
通过ArrayList 实现对数据的整理.用remove 删除.用add(index,object)进行添加.
结果:
del: [1,-1] add: [1,2]
del: [3,3] add: [5,5]
a<add>x</add>bcde
a<add>y</add><add>x</add>bcde
a<add>y</add><add>x</add><del>b</del>cde
a<add>y</add><add>x</add><del>b</del>cd<add>j</add>e
a<add>y</add><add>x</add><del>b</del>cd<add>j</add>e
最后显示了a变成b的全部过程.
