java - 如何在 java 中读取 YAML 文件?
问题描述
我有这样的 YAML 文件..
Product:
ProductA:
Suite:
SuiteName_A:
Environment_1: ["A","B","C"]
Environment_2: ["X","Y","Z"]
SuiteName_B:
Environment_1: ["E","F","G"]
Environment_2: ["K","L","M"]
ProductB:
Suite:
SuiteName_K:
Environment_1: ["A1","B2","C3"]
Environment_2: ["X1","Y1","Z1"]
已编辑----当我在一些阅读文章中阅读时,我创建了一些课程,这里是我想出的..
环境类
package Configuration;
import java.util.ArrayList;
public class Environment {
private ArrayList<String> Environment_1;
private ArrayList<String> Environment_2;
public ArrayList<String> getEnvironment_1() {
return Environment_1;
}
public void setEnvironment_1(ArrayList<String> Environment_1) {
this.Environment_1 = Environment_1;
}
public ArrayList<String> getEnvironment_2() {
return Environment_2;
}
public void setEnvironment_2(ArrayList<String> Environment_2) {
this.Environment_1 = Environment_2;
}
}
西装名称类
package Configuration;
import java.util.HashMap;
public class SuiteNames {
private HashMap<String,Environment> Suite;
public HashMap<String, Environment> getSuite() {
return Suite;
}
public void setSuite(HashMap<String, Environment> suite) {
Suite = suite;
}
}
产品类别
package Configuration;
import java.util.HashMap;
public class Product {
private HashMap<String,SuiteNames> Product;
public HashMap<String, SuiteNames> getProduct() {
return Product;
}
public void setProduct(HashMap<String, SuiteNames> product) {
this.Product = product;
}
}
主班
package Configuration;
import org.yaml.snakeyaml.Yaml;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
public class DbClass {
public static void main(String[] args) throws FileNotFoundException {
Yaml yaml = new Yaml();
InputStream inputStream = new FileInputStream("path");
System.out.println(inputStream);
Product product = yaml.loadAs(inputStream,Product.class);
System.out.println(product.getProduct());
}
}
这会产生以下错误:
Exception in thread "main" Cannot create property=Product for JavaBean=Configuration.Product@4c98385c
in 'reader', line 1, column 1:
Product:
^
Unable to find property 'Product' on class: Configuration.Product
in 'reader', line 2, column 3:
Check-in:
^
at org.yaml.snakeyaml.constructor.Constructor$ConstructMapping.constructJavaBean2ndStep(Constructor.java:270)
at org.yaml.snakeyaml.constructor.Constructor$ConstructMapping.construct(Constructor.java:149)
at org.yaml.snakeyaml.constructor.Constructor$ConstructYamlObject.construct(Constructor.java:309)
at org.yaml.snakeyaml.constructor.BaseConstructor.constructObjectNoCheck(BaseConstructor.java:216)
at org.yaml.snakeyaml.constructor.BaseConstructor.constructObject(BaseConstructor.java:205)
at org.yaml.snakeyaml.constructor.BaseConstructor.constructDocument(BaseConstructor.java:164)
at org.yaml.snakeyaml.constructor.BaseConstructor.getSingleData(BaseConstructor.java:148)
at org.yaml.snakeyaml.Yaml.loadFromReader(Yaml.java:525)
at org.yaml.snakeyaml.Yaml.loadAs(Yaml.java:519)
at Configuration.DbClass.main(DbClass.java:17)
Caused by: org.yaml.snakeyaml.error.YAMLException: Unable to find property 'Product' on class: Configuration.Product
at org.yaml.snakeyaml.introspector.PropertyUtils.getProperty(PropertyUtils.java:159)
at org.yaml.snakeyaml.introspector.PropertyUtils.getProperty(PropertyUtils.java:148)
at org.yaml.snakeyaml.constructor.Constructor$ConstructMapping.getProperty(Constructor.java:287)
at org.yaml.snakeyaml.constructor.Constructor$ConstructMapping.constructJavaBean2ndStep(Constructor.java:208)
... 9 more
我想获取环境名称列表并将其存储在列表中。我知道使用杰克逊 api。但我不知道如何将这些数据映射到类。我正在使用 servlet,并且在 servlet 内部我想要一个 java 方法来获取字符串列表。
解决方案
YAML有一个推荐的 Java 库列表: SnakeYAML、YamlBeans和eo-yaml
其中使用最广泛的可能是 SnakeYAML。Baeldung 在这里有一个非常容易理解的教程:https ://www.baeldung.com/java-snake-yaml
[编辑以解决新代码并在 OP 编辑中输出]:
您使用的格式和命名约定也有一些问题。在您的 yaml 文件中,任何列表都需要 [括号],实例变量需要为驼峰式,任何字符串都需要用引号括起来(包括字符串 HashMap 键):
products:
"ProductA":
suite:
"SuiteName_A":
environment_1: ["A","B","C"]
environment_2: ["X","Y","Z"]
"SuiteName_B":
environment_1: ["E","F","G"]
environment_2: ["K","L","M"]
"ProductB":
suite:
"SuiteName_K":
environment_1: ["A1","B2","C3"]
environment_2: ["X1","Y1","Z1"]
您应该尝试在您的 bean 命名约定中匹配它。此外,您的第二个设置者需要设置 Environment_2 而不是 Environment_1。这是您的实体类的外观。
环境
package Configuration;
import java.util.ArrayList;
public class Environment {
private ArrayList<String> environment_1;
private ArrayList<String> environment_2;
public ArrayList<String> getEnvironment_1() {
return environment_1;
}
public void setEnvironment_1(ArrayList<String> environment_1) {
this.environment_1 = environment_1;
}
public ArrayList<String> getEnvironment_2() {
return environment_2;
}
public void setEnvironment_2(ArrayList<String> environment_2) {
this.environment_2 = environment_2;
}
}
套房名称
package Configuration;
import java.util.HashMap;
public class SuiteName {
private HashMap<String,Environment> suite;
public HashMap<String, Environment> getSuite() {
return suite;
}
public void setSuite(HashMap<String, Environment> suite) {
suite = suite;
}
}
package Configuration;
import java.util.HashMap;
public class Product {
private HashMap<String, SuiteName> products;
public HashMap<String, SuiteName> getProducts() {
return products;
}
public void setProducts(HashMap<String, SuiteName> products) {
this.products = products;
}
}
编辑:在您的主要方法中,您可能希望使用 yaml.load(inputStream) 在 HashMap 中获取整个文件。根据您在评论中的问题,我添加了访问数据结构的内容。
数据库类
package Configuration;
import org.yaml.snakeyaml.Yaml;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.HashMap;
public class DbClass {
public static void main(String[] args) throws FileNotFoundException {
Yaml yaml = new Yaml();
InputStream inputStream = new FileInputStream("path.yml");
System.out.println(inputStream);
HashMap yamlMap = yaml.load(inputStream);
for (Object o : yamlMap.entrySet()) {
System.out.println(o);
}
// Access HashMaps and ArrayList by key(s)
HashMap products = (HashMap) yamlMap.get("products");
HashMap product = (HashMap) products.get("ProductA");
HashMap suite = (HashMap) product.get("suite");
HashMap suiteName = (HashMap) suite.get("SuiteName_B");
ArrayList environment = (ArrayList) suiteName.get("environment_1");
System.out.println(environment);
}
}
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