在java代碼中模板化多行字符串的簡單方法

Question

我經常遇到以下情況：我有很長的多行字符串，必須在其中注入屬性 - 例如模板之類的東西。 但我不想在我的項目中包含一個完整的模板引擎（如速度或自由標記）。

如何以簡單的方式完成此操作：

String title = "Princess";
String name  = "Luna";
String community = "Stackoverflow";

String text =
   "Dear " + title + " " + name + "!\n" +  
   "This is a question to " + community + "-Community\n" + 
   "for simple approach how to code with Java multiline Strings?\n" + 
   "Like this one.\n" + 
   "But it must be simple approach without using of Template-Engine-Frameworks!\n" + 
   "\n" + 
   "Thx for ..."; 

Answer 1

您可以使用幾行代碼來創建自己的小型模板引擎：

public static void main(String[] args) throws IOException {

    String title = "Princes";
    String name  = "Luna";
    String community = "Stackoverflow";

    InputStream stream = DemoMailCreater.class.getResourceAsStream("demo.mail");


    byte[] buffer = new byte[stream.available()];
    stream.read(buffer);

    String text = new String(buffer);

    text = text.replaceAll("§TITLE§", title);
    text = text.replaceAll("§NAME§", name);
    text = text.replaceAll("§COMMUNITY§", community);

    System.out.println(text);

}

和小的文本文件，例如在同一文件夾（程序包） demo.mail ：

Dear §TITLE§ §NAME§!
This is a question to §COMMUNITY§-Community
for simple approach how to code with Java multiline Strings? 
Like this one.
But it must be simple approach without using of Template-Engine-Frameworks!

Thx for ... 

Answer 2

一種基本的實現方法是使用String.format(...)

例：

String title = "Princess";
String name  = "Celestia";
String community = "Stackoverflow";

String text = String.format(
    "Dear %s %s!%n" +  
    "This is a question to %s-Community%n" + 
    "for simple approach how to code with Java multiline Strings?%n" + 
    "Like this one.%n" + 
    "But it must be simple approach without using of Template-Engine-Frameworks!%n" + 
    "%n" + 
    "Thx for ...", title, name, community);

更多信息

Answer 3

您可以在此處使用Java Resources來實現它
或者，您可以使用其他方法（例如HERE）保留當前使用的方法

Answer 4

您可以使用String#format() ：

String title = "Princess";
String name  = "Luna";
String community = "Stackoverflow";
String text = String.format("Dear %s %s!\n" +  
            "This is a question to %s-Community\n" + 
            "for simple approach how to code with Java multiline Strings?\n" + 
            "Like this one.\n" + 
            "But it must be simple approach without using of Template-Engine-Frameworks!\n" + 
            "\n" +
            "Thx for ...", title, name, community); 

Answer 5

Java沒有內置的模板支持。 您的選擇是：

• 使用現有的模板框架/引擎，
• 構建自己的模板框架/引擎（或類似模板），或
• 像在您的問題中一樣，編寫大量的“字符串打擊”代碼。

您可以使用String.format(...) ， MessageFormat和類似的代碼更簡潔地編寫上面的代碼，但是它們不會使您走得太遠……除非您的模板非常簡單。

---

相比之下，某些語言內置了對字符串插值，“此處”文檔或簡潔的結構構建語法（可適用於模板）的支持。

Answer 6

您可以為此使用java.text.MessageFormat ：

String[] args = {"Princess, "Luna", "Stackoverflow"};

String text = MessageFormat.format("Bla bla, {1}, and {2} and {3}", args);

Answer 7

使用 Java 15+：

String title = "Princess";
String name = "Luna";
String community = "Stackoverflow";

String text = """
        Dear %s %s!
        This is a question to %s-Community
        for simple approach how to code with Java multiline Strings?
        """.formatted(title, name, community);