Arthas之實例操作

1. 靜態(tài)類屬性操作

獲取public靜態(tài)屬性

ognl?-c?7cd84586?'@com.system.framework.ArtahsDemoClassLoader@pubTestPrex'
ognl?-c?7cd84586?"@com.system.framework.ArtahsDemoClassLoader@pubfinalTestPrex"

輸出各式 @Type[屬性值]，內(nèi)容如下

@String[static?public]
...
@String[final?static?public]

獲取private靜態(tài)屬性

ognl?-c?7cd84586?'@com.system.framework.ArtahsDemoClassLoader@privTestPrex'
ognl?-c?7cd84586?'@com.system.framework.ArtahsDemoClassLoader@privFnalTestPrex'

@String[static?private]
...
@String[final?static?private]

修改public靜態(tài)屬性,被final修飾，不能被修改

//?測試代碼想修改FINAL修飾符，結果沒有成功
@Test
public?void?testModifyFinal()?throws?Exception?{
??Field?finalField?=?this.getClass().getDeclaredField("privFnalTestPrex");
??finalField.setAccessible(true);
??System.out.println("==========初始值==========");
??System.out.println(finalField.get(null));
??Field?modiField?=?Field.class.getDeclaredField("modifiers");
??modiField.setAccessible(true);
??modiField.setInt(finalField,?finalField.getModifiers()?&?~Modifier.FINAL);
??finalField.set(null,?"修改后FInal");
??System.out.println("==========修改值==========");
??System.out.println(privFnalTestPrex);
}

靜態(tài)變量賦值，不能通過=直接賦值，需要采用反射的方式設置值

ognl?'#[email protected]@class,#f=#c.getDeclaredField("pubTestPrex"),#f.set(#c,"modify?static?public?")'

修改private靜態(tài)屬性,需要在反射時調(diào)用方法setAccessible,使private特殊轉化為public

ognl?'#[email protected]@class,#f=#c.getDeclaredField("privTestPrex"),#f.setAccessible(true),#f.set(#c,"modify?static?private?")'

2. 靜態(tài)類方法調(diào)用

靜態(tài)方法調(diào)用和靜態(tài)屬性一樣，格式為@class@method(args)

無參數(shù)調(diào)用

ognl?-c?7cd84586?'@com.system.framework.ArtahsDemoClassLoader@setPublicStaticMethod()'
ognl?-c?7cd84586?'@com.system.framework.ArtahsDemoClassLoader@modfiyPrivateStaticFiled()'

...
======第5次輸出======
源文件初始輸出==>static?public/static?private/testRefect--1/final?static?public/final?static?private
源文件初始輸出==>static?public/static?private/testRefect--2/final?static?public/final?static?private
======第6次輸出======
源文件初始輸出==>modify?by?method?static?public/static?private/testRefect--1/final?static?public/final?static?private
源文件初始輸出==>modify?by?method?static?public/static?private/testRefect--2/final?static?public/final?static?private
...
======第11次輸出======
源文件初始輸出==>modify?by?method?static?public/static?private/testRefect--1/final?static?public/final?static?private
源文件初始輸出==>modify?by?method?static?public/static?private/testRefect--2/final?static?public/final?static?private
======第12次輸出======
源文件初始輸出==>modify?by?method?static?public/modify?by?method?static?private/testRefect--1/final?static?public/final?static?private
源文件初始輸出==>modify?by?method?static?public/modify?by?method?static?private/testRefect--2/final?static?public/final?static?private
...

有參數(shù)調(diào)用

ognl?-c?7cd84586?'@com.system.framework.ArtahsDemoClassLoader@getPublicStaticMethod("input?params")'
...
ognl?-c?7cd84586?'@com.system.framework.ArtahsDemoClassLoader@getStaticPrivateMethod("input?params")'

@String[input?params?<==>?public?static?method?return?string]
...
@String[input?params?<==>?private?static?method?return?string]

從以上的測試結果來說，靜態(tài)方法不管是public還是private都可以直接調(diào)用。

3. 獲取非靜態(tài)類實例

查看某個類實例，無 --limit 參數(shù)默認10個

vmtool?-c?3e2e18f2?-a?getInstances?--className?*EncryptClass
vmtool?-c?3e2e18f2?-a?getInstances?--className?*EncryptClass?--express?'instances.length'
vmtool?-c?3e2e18f2?-a?getInstances?--className?*EncryptClass?--express?'instances[0]'

@EncryptClass[][
????@EncryptClass[com.system.framework.EncryptClass@3c573d32],
????@EncryptClass[com.system.framework.EncryptClass@68390fae],
]
...
@Integer[2]
...
@EncryptClass[
????note=@String[testRefect--1],
]

經(jīng)過上邊測試發(fā)現(xiàn)，一個類存在多個classloader加載時，需要指定classloader。但從返回結果看，返回了所有classloader加載的實例

4. 實例方法調(diào)用

調(diào)用實例 getNote 和 setNote 方法

vmtool?-c?3e2e18f2?-a?getInstances?--className?*EncryptClass?--express?'#val=instances[0],#val.getNote()'
vmtool?-c?3e2e18f2?-a?getInstances?--className?*EncryptClass?--express?'#val=instances[0],#val.setNote("modify?by?instance"+#val.getNote())'

@String[testRefect--1]

======第7次輸出======
源文件初始輸出==>static?public/static?private/testRefect--1/final?static?public/final?static?private
源文件初始輸出==>static?public/static?private/testRefect--2/final?static?public/final?static?private
======第8次輸出======
源文件初始輸出==>static?public/static?private/modify?by?instancetestRefect--1/final?static?public/final?static?private
源文件初始輸出==>static?public/static?private/testRefect--2/final?static?public/final?static?private

從控制臺輸出結果，對比第7次和8次輸出，我們可以發(fā)現(xiàn)第一個loader加載的class實例已經(jīng)成功修改了

5. 實例屬性操作

獲取或者修改第一個實例 note 屬性

vmtool?-c?3e2e18f2?-a?getInstances?--className?*EncryptClass?--express?'#val=instances[1].note'
vmtool?-c?3e2e18f2?-a?getInstances?--className?*EncryptClass?--express?'#val=instances[1],#val.note="modify?by?instance"+#val.note'

@String[testRefect--2]
...
======第121次輸出======
源文件初始輸出==>static?public/static?private/modify?by?instancetestRefect--1/final?static?public/final?static?private
源文件初始輸出==>static?public/static?private/testRefect--2/final?static?public/final?static?private
======第122次輸出======
源文件初始輸出==>static?public/static?private/modify?by?instancetestRefect--1/final?static?public/final?static?private
源文件初始輸出==>static?public/static?private/modify?by?instancetestRefect--2/final?static?public/final?static?private

從控制臺輸出結果，對比第121次和122次輸出，我們可以發(fā)現(xiàn)第二個loader加載的class實例已經(jīng)成功修改了

6. 條件操作

返回的對象集合，可以做二次篩選投影操作，也可以帶條件查詢符合的數(shù)據(jù)

vmtool?-c?3e2e18f2?-a?getInstances?--className?*EncryptClass?--express?'#val=instances'
vmtool?-c?3e2e18f2?-a?getInstances?--className?*EncryptClass?--express?'#val=instances.{note}'
vmtool?-c?3e2e18f2?-a?getInstances?--className?*EncryptClass?--express?'#val=instances.{#this.note}'
vmtool?-c?3e2e18f2?-a?getInstances?--className?*EncryptClass?--express?'#val=instances.{??#this.note.indexOf("1")>0}.{note}'

@EncryptClass[][
????@EncryptClass[com.system.framework.EncryptClass@52790e67],
????@EncryptClass[com.system.framework.EncryptClass@822cf83],
]
...
@ArrayList[
????@String[modify?by?instancetestRefect--1],
????@String[modify?by?instancetestRefect--2],
]
...
@ArrayList[
????@String[modify?by?instancetestRefect--1],
????@String[modify?by?instancetestRefect--2],
]
...
@ArrayList[
????@String[modify?by?instancetestRefect--1],
]

7.?總結

最近測試了Arthas很多命令,下篇將分享"各種監(jiān)控操作的黑魔法".歡迎感興趣的朋友關注我的訂閱號“小院不小”，或點擊下方二維碼關注。我將多年開發(fā)中遇到的難點，以及一些有意思的功能，體會都會一一發(fā)布到我的訂閱號中