最近由于工作需要,學(xué)習(xí)了ECLIPSE的COMPARE插件,并利用它進(jìn)行了兩個(gè)String的比較.

相關(guān)資料:
http://wiki.eclipse.org/FAQ_How_do_I_create_a_Compare_dialog%3F
http://wiki.eclipse.org/FAQ_How_do_I_create_a_compare_editor%3F
http://wiki.eclipse.org/FAQ_How_can_I_use_and_extend_the_compare_infrastructure%3F

另外ECLIPSE本身有一些對(duì)COMPARE擴(kuò)展得例子,可以從網(wǎng)站上下載.比如說(shuō)org.eclipse.compare.examples, org.eclipse.compare.examples.xml兩個(gè)插件分別擴(kuò)展了COMPARE插件使得可以對(duì)JAVA的PROPERTY文件和 XML文件進(jìn)行比較.這兩個(gè)例子插件都是擴(kuò)展COMPARE PLUGIN,使用EDITOR來(lái)顯示COMPARE結(jié)果.大家可以去看源代碼,這里就不多說(shuō)了.

下面主要說(shuō)一下我自己做的部分.
復(fù)用COMPAREDIALOG,來(lái)比較自己的東西,有兩種途徑:一種是繼承CompareEditorInput寫一個(gè)自己的INPUT,一種是實(shí)現(xiàn)CompareItem類.
我使用的是第一種途徑.
CompareConfiguration cc = new CompareConfiguration();
cc.setLeftLabel();
cc.setRightLabel();
CompareEditorInput finput = new MyCompareInput(cc);
首先建一個(gè)CompareConfiguration.這是個(gè)配置類,我們可以使用它來(lái)指定Comparedialog上顯示得一些東東.比如說(shuō)我們可以設(shè)置用來(lái)顯示互相對(duì)比的兩個(gè)字符串的左右兩個(gè)文本框的label(如上所示).
然后我們可以用這個(gè)配置類來(lái)構(gòu)建自己的INPUT類.比如說(shuō)這里是MyCompareInput.
這個(gè)類繼承CompareEditorInput,這樣才能作為openCompareDialog得輸入.
CompareUI.openCompareDialog(finput);
這樣就可以打開(kāi)ECLIPSE的COMPAREDIALOG進(jìn)行實(shí)際的比較了.
在MyCompareInput中我們需要提供一個(gè)方法來(lái)接受傳入的要進(jìn)行比較得兩個(gè)東西.比如說(shuō)我們?cè)诠ぷ鲄^(qū)中選了兩個(gè)文件,想要比較它們.我們就可以實(shí)現(xiàn)一個(gè)setSelection方法接受傳入得selection,然后再來(lái)得到這兩個(gè)文件.
我這里用了一個(gè)setStrings方法,來(lái)傳入兩個(gè)要比較的字符串.
在MyCompareInput中最重要得要實(shí)現(xiàn)的方法是prepareInput,比較字符串就是在這個(gè)方法里去比較得.
這這個(gè)方法中,比較得任務(wù)是由Differencer類去完成.這個(gè)類ECLIPSE已經(jīng)幫我們完成了.
Differencer d = new Differencer() {
protected Object visit(Object parent, int description,
Object ancestor, Object left, Object right) {
return new DiffNode((IDiffContainer) parent, description,
(ITypedElement) ancestor, (ITypedElement) left,
(ITypedElement) right);
}
};
使用時(shí)我們只需藥實(shí)例化這個(gè)類或者根據(jù)需要繼承這個(gè)類.
Differencer d = new Differencer();
實(shí)際得比較是用了Differencer的findDifferences方法.所以我們只需要用要進(jìn)行比較的兩個(gè)字符串,分別構(gòu)建一個(gè)實(shí)現(xiàn)ITypedElement接口的類,傳進(jìn)findDifferences去就行了.
d.findDifferences(false, pm, null, null, fLeftResource,fRightResource);
fLeftResource,fRightResource就是我們實(shí)現(xiàn)了ITypedElement得源.作為要進(jìn)行比較的源,我們還需要實(shí)現(xiàn) IStreamContentAccessor接口.IStreamContentAccessor接口只有一個(gè)需要實(shí)現(xiàn)的方法createStream,ECLIPSE用它來(lái)把要比較的東西構(gòu)建成一個(gè)輸入流.這樣COMPARE比較框架才能夠去一點(diǎn)一點(diǎn)的比較.下面是我實(shí)現(xiàn)得 fLeftResource的類.
class MyCompareNode extends BufferedContent implements ITypedElement {

private String fResource;

MyCompareNode (String resource) {
fResource = resource;
}

protected InputStream createStream() throws CoreException {
InputStream is = null;
is = new ByteArrayInputStream(fResource.getBytes());
return is;
}

public Image getImage() {
return null;
}

public String getName() {
return null;
}

public String getType() {
return ITypedElement.TEXT_TYPE;
}
}
針對(duì)不同的比較對(duì)象,createStream方法可以使用不同的方法來(lái)得到InputStream,只要能構(gòu)建成InputStream, eclipse就能進(jìn)行比較.另外getType方法可以返回三種類型:FOLDER_TYPE,TEXT_TYPE,UNKNOWN_TYPE.可以根 據(jù)需要自己選擇.
構(gòu)建完prepareInput方法,我們就完成了全部工作.就可以利用COMPARE框架來(lái)比較我們自己的東西了.

另一種方法是實(shí)現(xiàn)CompareItem類.這個(gè)可以去看
http://wiki.eclipse.org/FAQ_How_do_I_create_a_Compare_dialog%3F
eclipsefaq中有個(gè)例子CompareStringsAction .
這里的CompareItem也是需要實(shí)現(xiàn)IStreamContentAccessor,ITypedElement兩個(gè)接口的.

public class CompareStringsAction implements IWorkbenchWindowActionDelegate {
private static final int SECS_PER_YR = 60 * 60 * 24 * 365;
private ResourceBundle messages = ResourceBundle
.getBundle("org.eclipse.faq.examples.actions.CompareMessages");
private final Random rand = new Random();
private IWorkbenchWindow window;
public void dispose() {
}
private long getRandomDate() {
return System.currentTimeMillis() - (1000 * ((long)rand.nextInt(SECS_PER_YR)));
}
private String getRandomString() {
int len = rand.nextInt(200);
StringBuffer buf = new StringBuffer(len);
for (int i = 0; i < len; i++) {
buf.append((char) ('a' + rand.nextInt(26)));
}
return buf.toString();
}
public void init(IWorkbenchWindow window) {
this.window = window;
}
/**
* Opens a dialog allowing the user to select one from a group of random
* strings. The resulting selection is then displayed in a message dialog
*/
public void run(IAction action) {
//create several random string editions
final int count = rand.nextInt(20) + 5;
CompareItem[] items = new CompareItem[count];
for (int i = 0; i < items.length; i++)
items[i] = new CompareItem("String " + i, getRandomString(),
getRandomDate());
EditionSelectionDialog dialog = new EditionSelectionDialog(window
.getShell(), messages);
ITypedElement result = dialog.selectEdition(items[0], items, null);
if (result == null)
return;
String value = ((CompareItem) result).getString();
MessageDialog.openInformation(window.getShell(), "Your selection is...",
value);
}
public void selectionChanged(IAction action, ISelection selection) {
}
}

class CompareItem
implements
IStreamContentAccessor,
ITypedElement,
IModificationDate {
private String contents, name;
private long time;
CompareItem(String name, String contents, long time) {
this.name = name;
this.contents = contents;
this.time = time;
}
CompareItem(String name, String contents) {
this(name, contents, System.currentTimeMillis());
}
public InputStream getContents() throws CoreException {
return new ByteArrayInputStream(contents.getBytes());
}
public Image getImage() {
return null;
}
public long getModificationDate() {
return time;
}
public String getName() {
return name;
}
public String getString() {
return contents;
}
public String getType() {
return ITypedElement.TEXT_TYPE;
}
}