http断点续传简单实现（java)

/* SO jDtZ  
**SiteFileFetch.java {XUfxNDf  
*/ `8b6 /  
package NetFox; b42pLbpe'E  
import java.io.*; :DF4g=  
import java.net.*; 'C?f"P:X{  
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public class SiteFileFetch extends Thread { an5kR_=  
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SiteInfoBean siteInfoBean = null; //文件信息Bean m ?tnk?oX  
long[] nStartPos; //开始位置 b2@x(5#  
long[] nEndPos; //结束位置 u0H
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FileSplitterFetch[] fileSplitterFetch; //子线程对象 X}QmeY[0I  
long nFileLength; //文件长度 tMk>Bx9[  
boolean bFirst = true; //是否第一次取文件 ~ M>zO#U6  
boolean bStop = false; //停止标志 L$kAe1 V^m  
File tmpFile; //文件下载的临时信息 Rw^YTv  
DataOutputStream output; //输出到文件的输出流 XGl13@=O  
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//负责整个文件的抓取，控制内部线程（FileSplitterFetch类） <`p'6n79  
public SiteFileFetch(SiteInfoBean bean) throws IOException (cew:z H  
{ }AfPBfgC1z  
siteInfoBean = bean; M&T/vByTn_  
//tmpFile = File.createTempFile ("zhong","1111",new File(bean.getSFilePath())); _89G2)U=C  
tmpFile = new File(bean.getSFilePath()+File.separator + bean.getSFileName()+".info"); 1? hd  
if(tmpFile.exists ()) vl(v1[pU  
{ -
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bFirst = false; E4@fP]R+  
read_nPos(); H+&w7ER  
} q9(}wvtr  
else =F-^RnO%\  
{ tU2;Wb!Y  
nStartPos = new long[bean.getNSplitter()]; Br^b%12ZRS  
nEndPos = new long[bean.getNSplitter()]; e Em0c]]9  
} !!#ale&  
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} H 6<@  
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public void run() 3VBV_/i;  
{ sU!q~`; J  
//获得文件长度 =YsT
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//分割文件 ;mxT>|z  
//实例FileSplitterFetch 6oBt<r?CJ  
//启动FileSplitterFetch线程 5DUPsV  
//等待子线程返回 kYa' ] m  
try{ sjkl? _  
if(bFirst) 5h7DVr!  
{ }X:r:{r  
nFileLength = getFileSize(); ] CE2/6Ph  
if(nFileLength == -1) 4/vQ=t  
{ ^Wz{su2  
System.err.println("File Length is not known!"); 1vd+p!n  
} Kg67cmj)f  
else if(nFileLength == -2) w2V E_  
{ <v^.FxId  
System.err.println("File is not access!"); JPzPL\  
} >R-$JrU.=  
else sB!A:  
{ Wm_-T]#_  
for(int i=0;i<nStartPos.length;i++)  >S/>2e:  
{ 4D
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nStartPos = (long)(i*(nFileLength/nStartPos.length)); O$^YUHD  
} xGPv3TLH^  
for(int i=0;i<nEndPos.length-1;i++) (dZ&Af  
{ ,%<77LE  
nEndPos = nStartPos[i+1]; QKQy)g  
} Rznr9L  
nEndPos[nEndPos.length-1] = nFileLength; z [{%.kA  
} }]@ "t)"  
} q[g^[~WM#  
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|.yRo_  
//启动子线程 p]HtJt|]  
fileSplitterFetch = new FileSplitterFetch[nStartPos.length]; A":x<9   
for(int i=0;i<nStartPos.length;i++) =p:6u_@XWj  
{ d1TG[i<J_  
fileSplitterFetch = new FileSplitterFetch(siteInfoBean.getSSiteURL(), pTd@i1%Nr  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(), .kV/0!q?  
nStartPos,nEndPos,i); $>Do&T
U   
Utility.log("Thread " + i + " , nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); _uacpN/<|  
fileSplitterFetch.start(); I.x>mN-0  
} SY.V_O$l}  
// fileSplitterFetch[nPos.length-1] = new FileSplitterFetch(siteInfoBean.getSSiteURL(), wvY$s;  
siteInfoBean.getSFilePath() + File.separator + siteInfoBean.getSFileName(),nPos[nPos.length-1],nFileLength,nPos.length-1); XZJx3!~fm  
// Utility.log("Thread " + (nPos.length-1) + " , nStartPos = " + nPos[nPos.length-1] + ", 'UCL?$  
nEndPos = " + nFileLength); xNU}uW>>T  
// fileSplitterFetch[nPos.length-1].start(); &nn":  
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0'",4=c#V  
//等待子线程结束 E.brQx#}  
//int count = 0; uv4jbg}Z+3  
//是否结束while循环 i[swOYz]X  
boolean breakWhile = false; eyOAG4QTV  
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-)/>qFj)  
while(!bStop) +=v|kd  
{ >"b"
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write_nPos(); [aW#7  
Utility.sleep(500); w1Kyd?~%]  
breakWhile = true; e5Z\v0  
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for(int i=0;i<nStartPos.length;i++) '=5N?)  
{ 6gn|WO=Wf  
if(!fileSplitterFetch.bDownOver) 2
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{ )yJjJ:re  
breakWhile = false; `*B8IT)  
break; snrfHDhUw  
} XT\;2etVL  
} /TdTo@  
if(breakWhile) 7u;B[qH  
break; 5 m:nh<)#  
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//count++; BFY~::<b  
//if(count>4) *|'k  
// siteStop(); 'W)x<Iey1  
} CwAl-o  
6%? NNEM  
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System.err.println("文件下载结束！"); %(i(ZW "  
} ;:cM^LJ  
catch(Exception e){e.printStackTrace ();} x&sF_<[  
} 3WhJ,~o-y  
j_Fr3BWS  
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//获得文件长度 0kDT:3  
public long getFileSize() ,YH.n>`s+  
{ 
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int nFileLength = -1; >DDQ7 l  
try{ SngV<J>zR  
URL url = new URL(siteInfoBean.getSSiteURL()); ~"(1~7_  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); 3' ^ON  
httpConnection.setRequestProperty("User-Agent","NetFox"); g wk\[I`;  
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int responseCode=httpConnection.getResponseCode(); L\"$R":3{d  
if(responseCode>=400) ^b4o 0me  
{ wM><DrQ  
processErrorCode(responseCode); lps  
return -2; //-2 represent access is error wH<S0vl  
} Cnc77EUD  
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String sHeader; 371E S4  
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for(int i=1;;i++) L&eO?I=,  
{ %o~zsIl  
//DataInputStream in = new DataInputStream(httpConnection.getInputStream ()); v5&WW
?IBQ  
//Utility.log(in.readLine()); }3@`'i7  
sHeader=httpConnection.getHeaderFieldKey(i); y`'Ly@s  
if(sHeader!=null) "5{\0CfS  
{ ^ K/B[8  
if(sHeader.equals("Content-Length")) ]J~5{srq:  
{ &98qA
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nFileLength = Integer.parseInt(httpConnection.getHeaderField(sHeader)); A1i-QG/6  
break; $UKDXQF"  
} ]t<%v_K  
} L&l>?"_  
else j&8U:Q,  
break; ')_jK',1  
} t
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} =MMWcK&  
catch(IOException e){e.printStackTrace ();} yp8 .\.  
catch(Exception e){e.printStackTrace ();} tEb2>+R  
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wr  
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Utility.log(nFileLength); N#|c2n+  
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return nFileLength; .2OP>:9F  
} 594$X@!v  
9n$$D;  
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//保存下载信息（文件指针位置） ARslw*SJ  
private void write_nPos() Ie``Wb=  
{ G>cTqD6gT  
try{ *,mbZE=<  
output = new DataOutputStream(new FileOutputStream(tmpFile)); }**^g:  
output.writeInt(nStartPos.length); 5JQq?e)n  
for(int i=0;i<nStartPos.length;i++) l~!#<=.  
{ 3"%:S_[  
// output.writeLong(nPos); P%.9g  
output.writeLong(fileSplitterFetch.nStartPos); QD7>S(p  
output.writeLong(fileSplitterFetch.nEndPos); a ipvG  
} tBdvk>d  
output.close(); 76xgExOU?C  
} N/]TZu~k z  
catch(IOException e){e.printStackTrace ();} i9w xP i  
catch(Exception e){e.printStackTrace ();} ))u$j4V  
} <4^a(Zh  
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&:w{[H$-  
//读取保存的下载信息（文件指针位置） r0?`t!%V  
private void read_nPos() %kKtPrT  
{ ;p1%KmK3  
try{ BYP,}yzA  
DataInputStream input = new DataInputStream(new FileInputStream(tmpFile)); e(j"u;=  
int nCount = input.readInt(); ;z!~-ByzL  
nStartPos = new long[nCount]; dc"Vc 3)  
nEndPos = new long[nCount]; 0G;RMR':5  
for(int i=0;i<nStartPos.length;i++) P6;L\9=H<  
{ (]'4_
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nStartPos = input.readLong(); 1,BtOzuRo  
nEndPos = input.readLong(); ;<MHDmD  
} o{m$b2BW  
input.close(); <"aPoGda  
} m &c8@-T  
catch(IOException e){e.printStackTrace ();} XA>@0E>1r  
catch(Exception e){e.printStackTrace ();} `<q{
8  
} UP%X`  
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private void processErrorCode(int nErrorCode) d(42ob.Tr  
{ .
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System.err.println("Error Code : " + nErrorCode); %F1 Ce/  
} 7_n@iUG2n  
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b[VP"KZ?  
//停止文件下载 99H&#!~bSS  
public void siteStop() B4_0+K H  
{ h5.u W8  
bStop = true; `QAotSO+  
for(int i=0;i<nStartPos.length;i++) ^=F
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fileSplitterFetch.splitterStop(); Jc:*X4-'  
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} {BDp`uZ  
} gey`HhZp)  
//负责部分文件的抓取 ci6j"nKci  
**FileSplitterFetch.java &3'II:x(  
*/ 2U)H2%  
package NetFox; VO/" ot  
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import java.io.*; x^;nQas;  
import java.net.*; {pm>F}Cwy  
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public class FileSplitterFetch extends Thread { }`\+_@w  
0ppZ~}&  
}I9\=jT  
String sURL; //File URL a&M{y  
long nStartPos; //File Snippet Start Position iw
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long nEndPos; //File Snippet End Position >jq~5HN  
int nThreadID; //Thread's ID lX;2~iW{/  
boolean bDownOver = false; //Downing is over QY/36gK  
boolean bStop = false; //Stop identical W{?7Pn?1`  
FileAccessI fileAccessI = null; //File Access interface w<tr<Pu'  
{xMY2I++  
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public FileSplitterFetch(String sURL,String sName,long nStart,long nEnd,int id) throws IOException U8\[8~Xftn  
{ "fL:scq@0  
this.sURL = sURL; 5kof
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this.nStartPos = nStart; *U)!9DvA  
this.nEndPos = nEnd; bWW$_Spr  
nThreadID = id; 5NZob<<  
fileAccessI = new FileAccessI(sName,nStartPos);//定位 6&`.C/"2  
} uF+if`?  
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public void run() (sq4  
{ n[[rI0]g  
while(nStartPos < nEndPos && !bStop)
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{ w<lHY=z E  
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try{ >c|u|^3zt  
URL url = new URL(sURL); %}MZWf{  
HttpURLConnection httpConnection = (HttpURLConnection)url.openConnection (); Rq%g5lK  
httpConnection.setRequestProperty("User-Agent","NetFox"); AhZ8B'
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String sProperty = "bytes="+nStartPos+"-"; k^
}8=,j}  
httpConnection.setRequestProperty("RANGE",sProperty); :[ F`tDL  
Utility.log(sProperty); loZJV M  
&~29%Ns  
HW;,XzP=  
InputStream input = httpConnection.getInputStream(); Em N0K'x  
//logResponseHead(httpConnection); wyzj[PDS  
]s?BwLU6  
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byte[] b = new byte[1024]; ]j(2FM)#  
int nRead; ++W_4 B!  
while((nRead=input.read(b,0,1024)) > 0 && nStartPos < nEndPos && !bStop) k-@CcrepF  
{ &B1d+.+  
nStartPos += fileAccessI.write(b,0,nRead); rDX_$,3L  
//if(nThreadID == 1) <.s=)}'`P  
// Utility.log("nStartPos = " + nStartPos + ", nEndPos = " + nEndPos); HF" v \  
} 12M

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Utility.log("Thread " + nThreadID + " is over!"); ?g+0S@{i $  
bDownOver = true; y TfAS.  
//nPos = fileAccessI.write (b,0,nRead); u>Z;/kr  
} I2hX;pk,  
catch(Exception e){e.printStackTrace ();} I8;pMr6  
}
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} ?vuM'UH-  
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(.-3q;)6  
//打印回应的头信息 8;mn7XX  
public void logResponseHead(HttpURLConnection con) W2G`
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{ Ml1yk)3G  
for(int i=1;;i++) 3/+9#  
{ >Ip>x!wi  
String header=con.getHeaderFieldKey(i); cVv+,l4V0  
if(header!=null) T%A45BE V  
//responseHeaders.put(header,httpConnection.getHeaderField(header)); .%j&#(!  
Utility.log(header+" : "+con.getHeaderField(header)); fo9O+e s  
else xWWfts1t  
break; i% 19|an  
} vi')-1Y KM  
} 3YVG|Bc~_  
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public void splitterStop() mO;X>~K  
{ 6"U&i9  
bStop = true; Z[<rz6%cB  
} fz#e4+oH  
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} `VX]vumG  
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L\_MZ*<0[  
/* -fIX6  
**FileAccess.java ??0C"8:[  
*//文件访问(定位，写) E,&BP$B  
package NetFox; 6C@,&2<yK  
import java.io.*; Y+75}]B  
xtMN<4#E  
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public class FileAccessI implements Serializable{ :=WiT_M  
(1p[K-J)r  
//RandomAccessFile类用于在任意一个文件的特定位置上读/写字节 :bFCnV`Q  
RandomAccessFile oSavedFile; Nv}'"V>  
long nPos; Fw? ;Y%  
&^$dHr6v  
]o`qI#{R~R  
public FileAccessI() throws IOException Y^$^B,  
{ &.D3f"  
this("",0); ovJ#2_  
} rZ5vey  
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public FileAccessI(String sName,long nPos) throws IOException 7WK^eW"y8  
{ k4r;t: O^  
oSavedFile = new RandomAccessFile(sName,"rw"); ZlD\)6 dZ  
this.nPos = nPos; ?Iy$'am]L  
oSavedFile.seek(nPos); 7.)e4  
} =c>2d.^l  
rUvjc4O}  
}9yAYZ0q{b  
public synchronized int write(byte[] b,int nStart,int nLen) $/^DY&  
{ d#E]>:w
9  
int n = -1; (8DJ
f"}  
try{ m`luMt9  
oSavedFile.write(b,nStart,nLen); zvv<w@rX  
n = nLen; mOji\qia  
} :ad  
catch(IOException e) ParOWs~W/  
{ (XW\4msB)I  
e.printStackTrace (); fa7Z=:aG  
} iIWz\FM  
!]AM#LJ

 
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return n; OI0#@_L&  
} Ay\=&4dv  
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} _~V
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/* 8xs}neDg*  
**SiteInfoBean.java k L\;90  
*/ [>+R|;ln  
package NetFox; (IdXJvKU!  
>i^8K U  
sb"z=4  
public class SiteInfoBean { lbM)U  
ny# ?^.1  
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private String sSiteURL; //Site's URL l&3f<e  
private String sFilePath; //Saved File's Path iSDE6  
private String sFileName; //Saved File's Name 2d:<P!B  
private int nSplitter; //Count of Splited Downloading File 7|4t;F!  
\Tq !(]o^  
:|cC7,S  
public SiteInfoBean() n8W+q~sW%  
{//nSplitter的缺省值为5 kA3nhBH  
//default value of nSplitter is 5 6mcxp+lm|  
this("","","",5); vv='.R, D  
} DmDsn  

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public SiteInfoBean(String sURL,String sPath,String sName,int nSpiltter) `/]Th&(5  
{ D7q%rO|F'  
sSiteURL= sURL; 9 0PF)U  
sFilePath = sPath; }:JE*D|  
sFileName = sName; OZ{YQ}t{^1  
this.nSplitter = nSpiltter; qm RdO R  
:cDhqBMNr`  
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} >q W_%  
IE/F =Wr  
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public String getSSiteURL() {+D 6o  
{ \#1*r'V8  
return sSiteURL; TL^af
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} ahezDDR-.i  

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public void setSSiteURL(String value) -nBb -y  
{ S"t6 *fWr  
sSiteURL = value; TVaD',5_V%  
} rHS;wT  
&)(>e}es  
05$;7xnf(  
public String getSFilePath() c?@
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{ %V40I{1  
return sFilePath; c eH8  
} 7Jm&z/  
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public void setSFilePath(String value) >F@qFPN]  
{ N0Y$QWr_$  
sFilePath = value; R^_7B(  
} x3./  
}b$?t7Q)  
q?R)9E$h  
public String getSFileName() #Az#dt]H  
{ JCL+uEX4S  
return sFileName; kNC.^8ryz[  
} c~_nOd  
j@yK#==k  
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public void setSFileName(String value) |I; tBqN{u  
{ [73 \jT  
sFileName = value; {zTo[i  
} 9\yGv  
s& INcjC  
Z*AT &7  
public int getNSplitter() }]dK26pX  
{ R`IFKmA EJ  
return nSplitter; Qqp_(5S|>  
} ,F&TSzH[@v  
l|, Hj  
c"nowbf  
public void setNSplitter(int nCount) AXnuXa(j  
{ wiwAdYEQ\  
nSplitter = nCount; kAu-=X  
} 74[wZDW|(  
} $)HD`E  
x.5!F2$  
zm
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/* iy<|<*s2D  
**Utility.java lpjeEawo4  
*/ UR3qzPm!0e  
package NetFox; jTR>H bh  
d4#CZv[g/  
S.<aCN<@  
public class Utility { & bKl(,  
aUy!(Y  
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public Utility() 2HNAB4E  
{ Rm&^[mv  
u<g0oEs)  
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} S7B7'[ru  
p#\J
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//线程睡眠 KQf=t0Z=Ce  
public static void sleep(int nSecond) gwA+%]  
{ pmWt7 }  
try{ xJ$/#UdP  
Thread.sleep(nSecond); Q.U wtH  
} *]7$/%.D  
catch(Exception e) >U~{WM$"Y  
{ X7bS{GT  
e.printStackTrace (); Lhts4D/V7  
} vcmB)P-T`O  
} @#j?Z7E|  
eP?=tUB!S  
//日志 d3[O!4<T
  
public static void log(String sMsg) bQvhBa?  
{ f-!P[6bY  
System.err.println(sMsg); r6b;v2!8  
} Ah?,9r=U  
? PI2X.6  
O x),jc[/  
public static void log(int sMsg) 8v ZY+Q >  
{ 1_jd1UT  
System.err.println(sMsg); HM]mOmL90N  
} ;
4'pucq5/  
} Y'{F^VxA/  
n^t!+  
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/* <2V:tj)?P  
**TestMethod.java +F4SU(T  
*/ 2.2G79U,  
package NetFox; BN~gk~t_  
;ztt*py  
Yo*.? Mq'  
public class TestMethod { %K[u  
ls@j8bVv^  
s# 9*`K  
public TestMethod() {8pN]=SaJ~  
{ ///xx/weblogic60b2_win.exe ,+>JQ82  
try{ h]jy):9L  
SiteInfoBean bean = new SiteInfoBean("http://localhost/xx/weblogic60b2_win.exe","L:\\temp","weblogic60b2_win.exe",5); 6Bf a
B:  
//SiteInfoBean bean = new SiteInfoBean("http://localhost:8080/down.zip","L:\\temp","weblogic60b2_win.exe",5); T!%J x.^  
SiteFileFetch fileFetch = new SiteFileFetch(bean); KNG7$icG  
fileFetch.start(); .Cz9?]jyI  
} >X_5o^s2s  
catch(Exception e){e.printStackTrace ();} \0fk^  
)gHfbUYS  
mHF?t.y  
} @~CXnc0  
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public static void main(String[] args) v+vM:At4  
{ c0v6*O)  
new TestMethod(); k@[{_@>4^  
} V0G"Z6  
} Pk{%2\%&2  
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