Executing Stringified Source Code in Java 8 and Later
In this article take a look at how to execute a string that contains source code in Java 8 and later.
Executing stringified source code in Java is hard to realize with only jdk core libraries but, if we are going to use the CodeExecutor of Burningwave Core, the task will become simple and we can accomplish it in one of three different ways that we can choose:
- through BodySourceGenerator
- through a property located in Burningwave configuration file
- through a property located in a custom Properties file
Executing Code With BodySourceGenerator
For the first way, we must create a ExecuteConfig by using the within static method forBodySourceGenerator to which must be passed the BodySourceGenerator that contains the source code with the parameters used within: after that we must pass the created configuration to the execute method of CodeExecutor as shown below:
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package org.burningwave.core.examples.codeexecutor;
import java.util.ArrayList;
import java.util.List;
import org.burningwave.core.assembler.ComponentContainer;
import org.burningwave.core.assembler.ComponentSupplier;
import org.burningwave.core.classes.ExecuteConfig;
import org.burningwave.core.classes.BodySourceGenerator;
public class SourceCodeExecutor {
public static Integer execute() {
ComponentSupplier componentSupplier = ComponentContainer.getInstance();
return componentSupplier.getCodeExecutor().execute(
ExecuteConfig.forBodySourceGenerator(
BodySourceGenerator.createSimple().useType(ArrayList.class, List.class)
.addCodeRow("System.out.println(\"number to add: \" + parameter[0]);")
.addCodeRow("List<Integer> numbers = new ArrayList<>();")
.addCodeRow("numbers.add((Integer)parameter[0]);")
.addCodeRow("System.out.println(\"number list size: \" + numbers.size());")
.addCodeRow("System.out.println(\"number in the list: \" + numbers.get(0));")
.addCodeRow("Integer inputNumber = (Integer)parameter[0];")
.addCodeRow("return (T)new Integer(inputNumber + (Integer)parameter[1]);")
).withParameter(Integer.valueOf(5), Integer.valueOf(3))
);
}
public static void main(String[] args) {
System.out.println("Total is: " + execute());
}
}
Executing Code of a Property Located in Burningwave Configuration File
To execute code from Burningwave configuration file (burningwave.properties or another file that we have used to create the ComponentContainer: see architectural overview and configuration) we must add to it a property that contains the code and, if it is necessary to import classes, you must add them to another property named as the property that contains the code plus the suffix 'imports'. E.g:
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code-block-1=\
Date now= new Date();\
return (T)now;
code-block-1.imports=java.util.Date;
It is also possible to include the code of a property in another property:
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code-block-1=\
${code-block-2}\
return (T)Date.from(zonedDateTime.toInstant());
code-block-1.imports=\
${code-block-2.imports}\
java.util.Date;
code-block-2=\
LocalDateTime localDateTime = (LocalDateTime)parameter[0];\
ZonedDateTime zonedDateTime = localDateTime.atZone(ZoneId.systemDefault());
code-block-2.imports=\
static org.burningwave.core.assembler.StaticComponentContainer.Strings;\
java.time.LocalDateTime;\
java.time.ZonedDateTime;\
java.time.ZoneId;
After that, for executing the code of the property, we must call the executeProperty method of CodeExecutor and passing to it the property name to be executed and parameters used in the property code:
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package org.burningwave.core.examples.codeexecutor;
import java.time.LocalDateTime;
import org.burningwave.core.assembler.ComponentContainer;
import org.burningwave.core.assembler.ComponentSupplier;
public class SourceCodeExecutor {
public static void execute() {
ComponentSupplier componentSupplier = ComponentContainer.getInstance();
System.out.println("Time is: " +
componentSupplier.getCodeExecutor().execute("code-block-1", LocalDateTime.now())
);
}
public static void main(String[] args) {
execute();
}
}
Executing Code of a Property Located in a Custom Properties File
To execute code from a custom properties file we must add to it a property that contains the code and, if it is necessary to import classes, we must add them to another property named as the property that contains the code plus the suffix 'imports'. E.g:
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code-block-1=\
Date now= new Date();\
return (T)now;
code-block-1.imports=java.util.Date;
It is also possible to include the code of a property in another property:
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code-block-1=\
${code-block-2}\
return (T)Date.from(zonedDateTime.toInstant());
code-block-1.imports=\
${code-block-2.imports}\
java.util.Date;
code-block-2=\
LocalDateTime localDateTime = (LocalDateTime)parameter[0];\
ZonedDateTime zonedDateTime = localDateTime.atZone(ZoneId.systemDefault());
code-block-2.imports=\
static org.burningwave.core.assembler.StaticComponentContainer.Strings;\
java.time.LocalDateTime;\
java.time.ZonedDateTime;\
java.time.ZoneId;
After that, for executing the code of the property we must create an ExecuteConfig object and set on it:
- the path (relative or absolute) of our custom properties file
- the property name to be executed
- the parameters used in the property code
Then we must call the execute method of CodeExecutor with the created ExecuteConfig object:
package org.burningwave.core.examples.codeexecutor;
import java.time.LocalDateTime;
import org.burningwave.core.assembler.ComponentContainer;
import org.burningwave.core.assembler.ComponentSupplier;
import org.burningwave.core.classes.ExecuteConfig;
public class SourceCodeExecutor {
public static void execute() {
ComponentSupplier componentSupplier = ComponentContainer.getInstance();
System.out.println("Time is: " +
componentSupplier.getCodeExecutor().execute(
ExecuteConfig.forPropertiesFile("custom-folder/code.properties")
//Uncomment the line below if the path supplied is an absolute path
//.setFilePathAsAbsolute(true)
.setPropertyName("code-block-1")
.withParameter(LocalDateTime.now())
)
);
}
public static void main(String[] args) {
execute();
}
}
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