問題描述

在討論另一個問題時 我問了，@Aaron Digulla 指出了以下幾點:

While discussing another question I asked, @Aaron Digulla pointed out the following:

如果您安裝了 Java SDK，Java 安裝的根目錄中應(yīng)該有一個src.zip"文件.如果丟失，請重新下載 Java.當(dāng)您打開 JTable 類型(或單擊堆棧跟蹤中的行)時，Eclipse 應(yīng)該會自動找到源并顯示給您.

If you installed the Java SDK, there should be a "src.zip" file in the root directory of the Java installation. If it's missing, download Java again. Eclipse should find the source automatically and show it to you when you open the type JTable (or when you click on the line in the stack trace).

文件 src.zip 對我來說是存在的，但我仍然無法像@Aaron 所說的那樣訪問 JTable 的源代碼.可能是什么問題呢?如何用 Eclipse 解決這個問題?

The file src.zip is present for me, but I still can't access the source of JTable like @Aaron said. What could be the problem? How can I solve this with Eclipse?

未知來源"讓我擔(dān)心，盡管.這意味著您的 Java 版本沒有調(diào)試符號.確保你 a) 在使用 SDK 時開發(fā)，b)您的 SDK 包含調(diào)試符號，c) 不要告訴命令 java 去除調(diào)試符號當(dāng)它加載類時.

The "Unknown Source" worries me, though. it means your version of Java doesn't have debug symbols. Make sure that you a) use a SDK while developing, b) that your SDK contains debug symbols, c) don't tell the command java to strip debug symbols when it loads classes.

a) 我使用的是 Eclipse，為什么我不應(yīng)該使用 SDK?

a) I'm using Eclipse, why shouldn't I being using SDK?

b) 我如何知道我的 SDK 是否包含調(diào)試符號?如果沒有，我該如何添加它們?

b) How do I know if my SDK contains debug symbols? And if it doesn't, how can I add them?

c) 我如何檢查 Eclipse 是否告訴 java 去除調(diào)試符號?

c) How can I check if Eclipse is telling java to strip debug symbols?

很抱歉這些老生常談的問題，但我覺得我對 Java 開發(fā)過程并不完全了解.

Sorry for these banal questions, but I feel like I don't fully understand the Java development process.

推薦答案

a) Eclipse 自帶 Java 編譯器，所以如果你使用 Java Runtime Environment，你不會遇到很多問題，除了額外的像jarsigner 和可能的 JRE 源代碼可能會丟失.驗證安裝的最佳方法是通過包管理器；但是，如果您通過其他方式安裝，仔細(xì)觀察目錄通常可以區(qū)分兩者(見下文).

a) Eclipse comes with it's own Java compiler, so if you are using the Java Runtime Environment, you won't run into many issues, except that extras like jarsigner and possibly the JRE source code may be missing. The best way to verify your installation is through your package manager; however, if you installed by some other means, careful directory observation can usually differentiate the two (see below).

b) JRE 庫通常在不存在調(diào)試符號的情況下編譯.SDK 庫通常有它們.Java 調(diào)試是通過使用打開調(diào)試端口的命令行選項啟動 JVM 來完成的.SDK 與 JVM 對話，請求通過此端口設(shè)置斷點.稍后如果您決定單步執(zhí)行 JVM，它還會通過此端口發(fā)送單步/跳轉(zhuǎn)/倒帶調(diào)試命令.調(diào)試"符號實際上是 JVM 字節(jié)碼表，它引用從特定字節(jié)碼指令開始的有效源代碼行.這允許調(diào)試器將正在運行的字節(jié)碼與原始源代碼中的行號相關(guān)聯(lián).

b) JRE libraries are typically compiled without debugging symbols present. SDK libraries typically have them. Java debugging is done by starting the JVM with command line options which open a debugging port. The SDK talks to the JVM requesting breakpoints be set through this port. Later if you decide to step the JVM, it also sends the step / jump / rewind debugging commands through this port. The "debugging" symbols are actually JVM bytecode tables, which reference which line of source code is in effect starting at a particular bytecode instruction. This allows debuggers to associate the running bytecodes with line numbers in the original source code.

c) 通過(從菜單中)Window->Preferences(在選擇器列上)展開Java"，展開Java"下的Build Path"，然后選擇ClassPath variables"來驗證它.您將看到一些變量，包括一個名為JRE_SRC"的變量，它應(yīng)該指向包含面向公眾的 JRE 庫源代碼的 src.zip 文件.同時驗證 JRE_LIB 是個好主意.

c) Verify it by (from the menu) Window->Preferences (on the selector column) expand "Java", expand "Build Path" under "Java", and select "ClassPath variables". You will see a few variables, including one called "JRE_SRC", which should point to the src.zip file containing the public facing JRE library source code. It is a good idea to verify JRE_LIB at the same time.

JDK 主目錄通常包含一個bin"子目錄和一個jre"子目錄，因此如果您只看到一個bin"子目錄，則很有可能您位于 JRE 主目錄中.有了這些知識，希望您能夠解決剩下的問題.

A JDK home directory typically contains a "bin" sub-directory and a "jre" sub-directory, so if you only see a "bin" sub-directory, odds are good you are in a JRE home directory. With this knowledge, hopefully you'll be able to figure the rest out.

這篇關(guān)于如何使用 Eclipse 檢查調(diào)試符號狀態(tài)?的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網(wǎng)！